Special Construction Scheme for Tunnel of South to North Water Transfer Emergency Water Supply Project
1.1 The project location project is located near XX Village, XX Township, XX County, XX Province. The XX section of this bid has a total length of 6080 m with 1 degree of stake No. 208+130~214+210 and 3 degrees of stake No. (442+447.988)~(448+331.31). The project area is hilly landform, and the production and living facilities are easy to be arranged; The Class III highway from XX County to XX Zhangfang passes near the project area, with good external traffic conditions for construction. 1.2 Project introduction Large buildings: Lower XX tunnel; Water diversion structure: lower XX water diversion gate; Highway crossing buildings: West XX Highway Bridge, XX Highway Bridge; Drainage structures on the left bank: drainage culvert in the west XX ditch, drainage culvert in the east XX ditch, drainage inverted siphon in the west water north south ditch; Main canal: including excavated canal section and filled canal section. 1.2.1 Lower XX Tunnel: The building is located in the southwest of XiaXX Village, XX County, XX City, XX Province. It is one of the large buildings in the Middle Route Project of South to North Water Transfer. The project grade is Grade I. The grade of the main buildings is Grade 1, the design flow is 60m3/s, and the increased design flow is 70m3/s. The building starts at stake (443+136) and ends at stake (443+996), with a total length of 860m. The tunnel body section is 705m long, and Class III surrounding rock is 305m long, accounting for 43.2% of the tunnel length; Class IV and V surrounding rocks are 400m long, accounting for 56.8%. The longitudinal slope of the tunnel is 1/9000, with double tunnel lines. The tunnel body is a horseshoe shaped section without pressure flow, and reinforced concrete full section lining is adopted. The inlet and outlet sections of the tunnel are 70m and 85m long respectively, both of which include straight twisted surface section, rectangular groove transition section, maintenance gate chamber section and culvert section. The soil slope is protected by mortar masonry; Rock slope is protected and built with anchor rod and steel mesh shotcrete. 1.2.2 Lower XX water diversion outlet gate: located at the main channel stake number (444+800), the designed water diversion flow is 3m3/s, which consists of three parts: inlet section, gate chamber section, and embankment culvert section. The total length of the building is 36.3m. 1.2.3 West XX Highway Bridge: located at the main canal stake number (444+905), the included angle between the centerline and the main canal centerline is 90o, which is a through truss arch bridge. The upper structure of through truss arch bridge is composed of two truss beams, which are prefabricated with C30 concrete. Cast in situ C25 concrete transverse connecting beam at the ends of two trusses and the middle part of the upper chord span, and lay precast C30 concrete bridge deck at the lower chord. Two layers of pavement are set on the bridge deck, the lower layer is C30 waterproof concrete triangle cushion, the cross slope of the bridge deck is 1%, and the upper layer is 5cm thick asphalt concrete pavement. A vertical curve is set on the bridge deck to ensure that the rainwater on the bridge deck is discharged to both banks. Safety belts and steel pipe railings are set on both sides of the bridge. The left and right bank approaches are 173m long, the longitudinal slope of the approach is 5.0%, and the radius of the mid span vertical curve is 2000m. The pier is of pile type, with a pile diameter of 110cm and a column diameter of 100cm, and a tie beam is set at the top of the column. C25 is used for abutment column, cast-in-place pile and tie beam concrete. 1.2.4XX highway bridge: located at the main channel stake number (447+730), the included angle between the center line and the main channel center line is 90o. It is a 35m span reinforced concrete prestressed T-beam bridge with a single span layout. The prestressed T-beam is prefabricated with C40 concrete, and the prestressed reinforcement is 24 φ 5 cold drawn carbon round steel wire bundles. The standard width of T-beam flange plate is 160cm, and the width of side beam is adjusted according to the actual situation, and the beam height is 200cm. The left and right bank approaches are 176m long, the longitudinal slope of the approach is 3.0%, and the midspan vertical curve radius is 2500m. The pier is of pile type, with pile diameter of 120cm, bridge column diameter of 110cm, capping beam width of 130cm and height of 80cm. The abutment is U-shaped mortar masonry abutment with expanded foundation, which is constructed with M7.5 mortar. The strength grade of pile foundation concrete is C25, and that of pier column and cap beam is C30. 1.2.5 The drainage culvert of West XX Ditch is located at the stake No. 445+025.2 of the main channel and consists of the inlet and outlet connection section, transition section, tunnel body section, etc. Both sides of the entrance and exit transition section are splayed and arc concrete gravity retaining walls. The top elevation of the entrance wall is 55.27m, 25m long, and the top elevation of the exit wall is 55.02m, 30m long. The bottom is protected by 0.4m thick mortar masonry. The tunnel body section is a three hole reinforced concrete box structure with a single hole discharge section size of 4.0m × 3.5m. The tunnel body is 90m long, and an expansion settlement joint is set at 10m, and seepage intercepting ring and double rubber waterstop are set at the joint. The inlet and outlet connecting sections are part of the downstream energy dissipation and erosion prevention. The inlet section is 74.0m long and the outlet section is 57.06m long. 0.5m thick mortar rubble is used for slope protection and 0.4m thick mortar rubble is used for bottom protection. A stilling pool is set at the outlet, with a length of 12.0m and a depth of 0.5m. The bottom is protected by 0.5m thick reinforced concrete. Anti scour groove is set at the tail of outlet, with bottom width of 2.0m and groove depth of 2.0m. 1.2.6 The drainage culvert of East XX Ditch is located at the main channel stake No. 445+821.7, which is composed of inlet and outlet connection section, transition section, tunnel body section, etc. On both sides of the entrance and exit transition section are splayed and arc concrete gravity retaining walls. The top elevation of the entrance wall gradually changes from 56.2m to 54.0m, 20m long, and the top elevation of the exit wall gradually changes from 54.0m to 56.0m, 20m long. The bottom is protected by 0.5m thick reinforced concrete and 0.4m thick mortar masonry. The tunnel body section is a two hole reinforced concrete box structure with a single hole discharge section size of 4.0m × 4.0m. The tunnel body is 84m long, and an expansion settlement joint is set at 10m, and seepage intercepting ring and double rubber waterstop are set at the joint. As a part of downstream energy dissipation and erosion prevention, the inlet and outlet connecting sections are 30.0m long and 57.06m long, with 0.5m thick masonry slope protection and 0.4m thick masonry bottom protection. In addition, the drainage culvert of DongXX Ditch also has traffic requirements. In order to ensure the structural safety of the culvert when driving, in addition to laying 10cm thick high-grade concrete wearing course on the bottom plate, curbs with a width of 25cm and a height of 25cm are set on both sides of the tunnel bottom, and drainage pipes are set under the curbs; In order to restrict the entry of superelevation vehicles, lane separation piers and anti-collision barriers are set at the entrance and exit. 1.2.7 Xishui Beinangou drainage inverted siphon: located at the main channel stake number (448+080), the included angle between the center line and the main channel center line is 77o, the building flood standard is designed according to the 50 year return period flood, the 200 year return period flood check, the design flood flow is 67m3/s, and the check flood flow is 113m3/s. The inverted siphon body surface is a three hole 2.6 × 2.6m box culvert, which is composed of inlet and outlet connecting sections, transition sections, sand basins and pipe body sections. The total length of the building is 179.5m. 1.2.8 The total length of the open channel section of the main channel in this section is 5220m, of which the length from the starting point of this section to the inlet of the lower XX tunnel is 688.4m, and the length from the outlet of the lower XX tunnel to the end of this section is 4531.6m. The design flow is 60m3/s, and the increased design flow is 70m3/s. The bottom width of the tunnel inlet open channel is 12.5m, the internal slope is 1:0.75, the longitudinal slope is 1/22000, and the design water depth in the channel is 4.3m; The bottom width of the tunnel outlet open channel is 7.0m, the internal slope is 1:2.5, the longitudinal slope is 1/22000~1/24000, and the design water depth in the channel is 4.3m. The channel is half excavated and half filled, and half excavated and half filled. There are 690m stone channels at the entrance and exit of the lower XX tunnel, and the others are earth channels. Flood embankment or protective dam shall be set outside the opening line on both sides of the channel. The overflow section of the earth channel is trapezoidal, which is lined with cast-in-place concrete. The lining thickness is 10cm for the slope and 8cm for the bottom plate. The special parts are properly thickened, and the lining elevation is up to the level I catwalk. The concrete lining plate is divided into a joint about 4m vertically and horizontally (the longitudinal side of the channel slope is a half cut joint, and the joint width is 1cm). The other side is a through joint with a width of 2cm. The upper part of the joint is filled with 2cm thick polysulfide sealant for open channel, and the lower part is filled with polyethylene closed cell foam plastic plate. The 3000 m canal section is paved with composite geomembrane to strengthen seepage prevention, and the 1700 m canal section is paved with polystyrene foam plastic plate to prevent frost heaving. The cross section of the Shiqu canal is trapezoidal, which is lined with cast-in-place concrete. The lining thickness of the slope and the bottom of the canal is 15cm, and the lining elevation is up to the level I catwalk. The concrete lining plate is divided into a joint about 8m vertically and horizontally, which is 2cm wide. The upper part of the joint is filled with 2cm thick polysulfide sealant for open channel, and the lower part is filled with polyethylene closed cell foam plastic plate. The inner slope of the channel above the first level packway and the outer slope of the channel in the half cut and half fill and full fill sections are protected by hexagonal hollow concrete frame (20cm side length, 3cm width and 10cm thickness) with turf planted inside. The outer slope toe of the channel section with a filling height of more than 8m is provided with horizontal drainage and made of dry stone pitching with a height of about 2.0m. Drainage ditches (pipes) are used for drainage on the internal and external slopes. A 8m wide forest belt is set in the excavation section starting from the protective dam on the top of the embankment, and an 8m wide forest belt is set outside the outer slope toe of the channel in the filling section. Interception and diversion ditches are set outside the forest belts on both sides, and mortar masonry slope protection is adopted. The isolation fence is set at 1m outside the intercepting ditch. The main materials are plastic impregnated metal mesh and φ 48 plastic impregnated steel pipe. The fence is 2.0m high, and a concrete support is set at an interval of 2.0m. The length, width and height of the support are 0.4m, 0.4m and 0.5m respectively. An operation and maintenance road is set on the primary berm (or embankment top) of the channel, with a clear width of 4m. The right side is asphalt concrete pavement, and the left side is clay bound macadam pavement. Curbs and warning posts shall be set on the inside of the canal and the outside of the filled canal. 1.2.9 Buildings involving metal structure equipment in the main canal project of this bid section include lower XX tunnel and lower XX water diversion gate. There are 2 holes in the lower XX tunnel, and the buildings involving metal structure equipment include: inlet bulkhead gate and outlet bulkhead gate. One bulkhead gate and its hoisting equipment shall be set at the inlet bulkhead gate; The outlet bulkhead gate is equipped with one bulkhead gate and its hoisting equipment. The building has two bulkhead gates and two electric hoists. The main materials of the gates are Q235B, and the main materials of the embedded parts are Q235B and 1Cr18Ni9Ti. The total weight of the metal structure equipment is 50.8t. There is one hole in the lower XX water outlet gate, which is equipped with one hole access gate slot, one plane sliding cast iron service gate, and one manual and electric screw hoist. The material of plane sliding cast iron service gate is HT20-40, the material of embedded parts of bulkhead gate slot is Q235B, and the total weight of metal structure equipment is 5.6t. The above two buildings have two bulkhead gates, two electric hoists, one hole bulkhead gate slot, one plane sliding cast iron service gate, and one manual and electric screw hoist. The total weight of metal structure equipment is 56.4t. 2. Hydrometeorology and engineering geology 2.1 Hydrometeorology This section belongs to temperate and warm temperate continental monsoon climate zone, with significant seasonal difference. According to the statistics of meteorological stations near the canal line, the extreme minimum temperature is - 24.7oC, the extreme maximum temperature is 41.9oC, the annual average wind speed is 2.2m/s, the maximum wind speed is 28m/s, and the wind direction is WNW; The annual average frost free period is 180 days, the earliest date of the first frost is October 18, and the latest date of the last frost is April 20; The average freezing days for many years are 68 days, the earliest freezing period is November 21, and the latest thawing period is March 18. The maximum frozen soil depth is 75cm, and the average annual water surface evaporation is 1571mm (20cm evaporation pan); Annual average sunshine duration is 2590h. See Table 1-1 for the average monthly temperature for many years. Table 1-1 Average Monthly Temperature for Many Years Table (℃) Temperature of Month 1 2 3 4 5 6 7 8 9 10 11 12 - 5.1 - 2.2 5.1 13.7 20.0 24.5 26.0 19.6 12.7 4.0 - 3.0 11.7 The average annual precipitation in this basin is 700 mm, and July and August account for about 70% of the annual precipitation. The precipitation varies greatly from year to year, and the precipitation in wet year and dry year is about 3 times different. The area near Zijingguan in the middle and upper reaches is closer to the rainstorm center of Langya Mountain, which is the area with the largest precipitation in this basin. The precipitation gradually decreases to the west, north and east. 2.2 Engineering geology 2.2.1 Geological overview 2.2.1.1 Topography and geomorphology This canal section is located in the border zone between the eastern foot of Taihang Mountains and the North China Plain. The terrain is generally high in the west and low in the east. The channel section is hilly landform with a total length of 6080m, including 860m of lower XX tunnel and 5220m of channel length. 2.2.1.2 Stratigraphic Lithology The surface of this canal section is mostly covered by the Quaternary stratum. According to the geological mapping and drilling, the stratum lithology developed in this canal section mainly includes: Jixian Tieling Formation dolomite, Qingbaikou Xiamaling Formation shale, Changlongshan Formation quartz sandstone, shale, Cenozoic Quaternary loose stratum and artificial accumulation. 2.2.1.3 Geological structure This canal section is located at the eastern edge of Taihang Mountain uplift, a tertiary structural unit, bordering XX fault depression of tertiary structural unit. The main regional fault structures include Babaoshan fault, Tongxian Nanyuan fault, Daxing fault, XX fault, XX fault, East XX fault, Xushui fault and Zijingguan fault. According to the Zoning Report of Design Ground Motion Parameters along the Middle Route of South to North Water Transfer Project proposed by the Analysis and Prediction Center of the National Seismological Bureau in April 2004, the peak ground motion acceleration of this canal section is 0.10g (equivalent to the basic seismic intensity VII zone). 2.2.1.4 Hydrogeological conditions Groundwater in the canal section is mainly karst fissure water. It mainly occurs in dolomite, limestone karst fissure and hole aquifer, and is distributed in low mountains and hills. It has strong or extremely strong water permeability and strong or strong water yield. The groundwater level is below the bottom of the canal, which has little impact on the canal construction. The surface water and groundwater in the canal section are not corrosive to the concrete. 2.2.2 Engineering geological conditions and evaluation of the lower XX tunnel 2.2.2.1 Topography and geomorphology This area is a hilly area in the transitional zone between the eastern foot of Taihang Mountains and the North China Plain. The Xiwu Mountain through which the tunnel passes is the near end of a NW-SE mountain range, with the top elevation of 160.0~170.0m, the entrance and exit of the ridge terraces, and the ground elevation of 65.0~70.0m. Xiwu Mountain is a denuded hill with exposed bedrock on the top and relatively developed gullies. There are two gullies at the inlet, with a V-shaped section. The outlet gully is branched, with a cutting depth of 3-6m, and bedrock on both sides and bottom of the gully is exposed. 2.2.2.2 Stratum lithology In the building area, the stratum lithology from old to new is: ① Jixian Tieling Formation (Jxt): medium thick layer of gray and gray white chert banded dolomite, hard rock, rock strike NW310 °～ 330 °, dip NE, dip angle 15 °～ 30 °, locally exposed on the surface at the tunnel exit. ② Qingbaikou Xiamaling Formation (Qnx): mainly composed of shale and sandy shale. Shale is grayish purple, purplish red, grayish yellow, flaky and weak. Shale is slightly crumpled and slightly metamorphosed. The occurrence trend of tunnel body rock stratum is NW3200~330 °, dip to SW, and dip angle is 10 °~25 °; The attitude of the rock stratum at the outlet strikes NW320 °~330 °, dips NE, and dips 25 °~35 °. This layer is mainly distributed from the tunnel body (443+550) to the exit section. ③ Qingbaikou Changlongshan Formation (Qnc): mainly composed of quartz sandstone, siltstone and shale. Shale: gray, yellow, flaky, with small interlaminar wrinkles; Siltstone: gray, grayish white, greenish gray, sand grain composition is quartz; Medium coarse grained quartz sandstone: grayish white, greenish gray, hard and brittle, with quartz vein intrusion. The strata strike NE10 °～ 30 ° and dip NW ∠ 15 °～ 32 °. ④ Quaternary middle Pleistocene slope eluvial (dl+elQ2): reddish brown clay mixed with gravels, with gravel content of 30%~70%, mainly composed of dolomite. It is mainly distributed at the tunnel outlet and gully, with layer thickness of 1~3m. ⑤ Quaternary upper pleistocene alluvial proluvial (): loess like loam, grayish yellow, dry~slightly wet, hard plastic, 2~4m thick, with vertical joints and macropores, and a large number of plant roots. It is mainly distributed in the entrance and exit terraces. ⑥ Quaternary Holocene upper slope eluvium (): composed of loam and clay mixed with gravel, with a thickness of 0.2~6m. It is distributed in gullies and part of the surface.
