1.1 project overview
Gang Xia station of Shenzhen Metro first phase project of a station on Line 1 line, caitian Road Interchange, it is located in fuhualu and underground, below the station at fuhualu, cross the caitian road, was something to the layout. Mileage stations effective platform length Center for CK7+194.951.
Station buildings and dense population around, fuhualu and caitian road traffic is heavy. In fuhualu and caitian road at the intersection of the corners for a high-rise building, Western North and South sides of the station for the eight-story buildings with poor structure. Station range many of underground pipeline, including rainwater, sewage, water supply, gas, electricity cables and more than 30 articles, caitian road and West of rain and sewage pipe buried 4m, caitian Road East, in particular over 110,000-volt cable buried in the station. In the southwest side of the station at 14m has a larger section of cable tunnel.
Main structure of the station for the underground two-level three-span frame structure, length 220.1M, w 21.9m, high 12.8M, buried deep 16m. Station and the surrounding environment as described in Figure 1-General Plan of the station.
1.2 structure of the station design requirements
Gang Xia station structural design except those that meet the General design requirements of a metro station, during the bidding, the preliminary design of the station and the ensuing construction drawing design, paying authority, the power supply Bureau of Shenzhen Municipality, owners of land planning Bureau, and expert on station design proposed by a number of special requirements, involving mainly has following several points on the structure;
(1) in 8 months during the construction of the station, caitian road half-up construction, half-up, requires opening and opened to traffic after 8 months of full frame.
(2) modified to move the 110,000-volt cable costs, and nowhere to migration, protection measures require station construction to take place, and ensure the normal supply.
(3) within the caitian Road station under the roof to fall as low as the ground 4.5M, caitian road rain, pipe laying, to meet requirements. Resulting station Office floors in the Central lower atrium of owners requested the Office, so that the Office for the station and platform layers into one, increase the height of Visual effects.
(4) the station underground continuous wall of exterior-protected structure is not used, recommended the rectangle of low cost manual hole digging pile.
1.3 engineering geological and hydrogeological conditions
Stations in the area of artificial stacked layers overlying Quaternary Holocene (Q4ml), alluvial (Q4al) and the residual layer from the Quaternary (Q4el), underlying yanshanian Granites (r53) throughout geological Profile of distribution as described in Figure 2 at the station.
Engineering geological conditions of 1.3.1
(1) artificial accumulation layers
① the effect of filling (silty clay): mainly to the hard State, local hard plastic, containing sand and small gravel, for compression, layer thickness 0~8.0M. for class ⅱ, ⅰ type of surrounding rock.
② effects fill (clay): mainly to the hard State, and local hard plastic, plastic, compression in soil, slice thickness 0~7.5M, for class ⅱ, ⅰ type of surrounding rock.
(2) alluvium
① Clay: mainly to the hard State, local hard plastic, plastic, containing local gravel, slice thickness 0~5.9m. for class ⅱ, ⅱ class surrounding rock.
② the silty soil: mainly hard plastic State, a local soft plastic, hard, with gravel, for highly compressed soil, slice thickness 0~6.8M. for class ⅱ, ⅱ class surrounding rock.
③ silt: loose, wet ~ saturated, partially containing powder, clay and a small amount of organic matter, slice thickness 0~4.1M. for class ⅰ soil, I rock.
④ in the sand: loose ~ and dense, saturated, containing powder, clay, layer thickness 0~4.9m. for class I, class I rock. ⑤ coarse sand: loose ~ a little dense, saturated, containing powder, clay, layer thickness 0~3.4m. for class I, class I rock. These sands are located in the western end of the station and junction of interval.
(3) the residual layer
① sandy clay soil: mainly to the hard State, local hard plastic, plastic, soft plastics, as a highly compressed soil, slice thickness 0~16.0M. for class III, class ⅱ rock.
② gravelly clay soil: mainly to the hard State, local hard plastic, plastic, for highly compressible soil, thick 0~17.7m. For class III, class ⅱ rock.
(4) granite
① total weathered granite: clips of gravel, compressible soil, top buried depth of 18.0~25.2m. for class III soils, ⅱ class surrounding rock.
② high winds of granite: gravel, top buried depth 20.0~28.0M. as a class IV soils, ⅲ rock.
③ medium weathered granite: fragments and short cylindrical, top buried depth of 22.1~30,5m. for class v soils, ⅲ rock.
④ breeze of granite: cylindrical, jointed development, top buried depth of 22.5~31.6m. for class VI soils, v class surrounding rock.
1.3.2 hydrogeological condition
Groundwater occurrence in this venue media porosity dive is the fourth line and bedrock fissure water.
Quaternary pore diving major occurrence in sandy soils, clayey soil and in residual soils, strong water permeability soil layer with moderately permeable sand class ~, and residual layer of clay with weak water permeability, relative barrier.
Bedrock fissure water occurrence in Granites in the regolith, weathered granite rocks with low water permeability, relative isolation layers, highly weathered and middle permeability of medium-weathered rocks.
Exploration of buried depth of groundwater during 1.5~4.3M, elevation 4.27~1.19m, the water level luffing 0.5~1.5m. with low corrosion of steel structure of groundwater, groundwater to paragraph CK7+175~CK7+341.101 of reinforced concrete structure with a low solubility, secondary decomposition corrosion, integrated evaluating its corrosion-corrosion medium.
2, station structural design characteristics
2.1 using rectangular artificial Dig-hole pile retaining structure of the station, and also for side wall of main structure of the station
Gang Xia station design tender scheme of exterior-protected construction for underground continuous wall, after expert review, proposed underground wall cost high, may use the lower cost of manual hole digging pile. We HA points around the pit displacement characteristics of high, rectangular mortise artificial digging hole pile 1X1.5m, works well in its entirety and waterproofing, in horizontal displacement of pile subjected to lateral pressure smaller. For strengthening pile of overall stiffness and waterproof performance, design has Tenon received of AU pile and convex pile, in Tenon received Department set plate butyl rubber PuTTY check water with and the case water expansion rubber check water article, and in AU pile sides level reinforced end Department pre-buried and convex pile level reinforced connection of reinforced connection manager, makes rectangle dug hole pile overall sexual similar Yu underground continuous wall.
Caitian road as soon as possible, because recovery full frame opening roof to inverse construction method of construction of the station, the corresponding station structure embedded within the pile of plates and pile by the steel Connector connection, inverse side wall when using single-layer wall-building than the double wall construction, also saving the liners, while rectangular excavated pile thickness design of station structure can meet the requirements of 1M. Waterproof increasing water-proof layer, that is, with cement-based permeable crystallization type waterproof coating inside of the Scribble rectangle hole digging pile and end of height from roof to floor and roof, floor and pile surface of vertical set PuTTY for water swelling water stop. Therefore HA points rectangular artificial digging hole pile retaining structure of both stations, and as a side wall of the main structure of the station.
2.2 semi-amplitude of Central station construction and commissioning of the semi-amplitude of structural measures
Under caitian Road East half site station first construction of requirements, to in station central 8 months construction during guarantee caitian road half site construction, and half site opening, we in caitian road Middle near set station Eastern pit seal head pile, seal head pile used φ 800 drilling perfusion pile, since ground deep to pit under 8M, and set three road angle pole, makes Eastern pit excavation Shi, caitian Road West half site continues to opening. Caitian Road East Half frame roof while pouring in reverse at the station building, caitian Road East of, and at the pile head on the roof of building two reinforced concrete retaining walls 0.5m thick, caitian Road East, so that the half-amplitude recovery after the opening of retaining wall under the vehicle and the road of soil layer under lateral pressure. Caitian road after the opening of eastern half piece, may proceed with the Western half of sites excavation, support, and reverse construction of the building’s roof, caitian road on the Western side of the roof, and build a 0.5m thick reinforced concrete retaining walls, caitian road can be realized after the casing on the roof opening of the full frame.
2.3 half-reverse construction method of building in the middle of the station, others Shun building construction
Caitian road as soon as possible, in order to achieve the full-opening of the site during construction, reverse construction method of roof in the middle of the station. Roof and roof beams supported on a concrete filled steel Tubular column and hole-digging pile. Strength of concrete filled steel tubular columns high, bearing, and construction. Due to the effects of 4.5m on the roof, each bearing capacity of concrete-filled steel tube column of more than 1 GB. 16Mn steel for steel tube concrete columns with outer diameter is 0.6m 20mm mm thick made of steel tube, steel C40 concrete poured in. Artificial digging pile foundation under column for PHI 1600, pile bottom expansion for φ 2,600, bearing on the stroke of granite. For the station Hall and concrete filled steel Tubular column connection Panel longitudinal beams and bottom longitudinal beams, in the appropriate parts on the steel pipe tensile, shear steel welding, parts of longitudinal tensile reinforcement beam welding on the tensile steel plate, shear plate shear transfer of vertical beams to concrete filled steel Tubular column.
Inverse built most of end bearing capacity of soil layer of roof above the 100kPa, 100kPa needed after the replacement of soil layer construction of soil mould, pour roof.
Inverse outside in addition to the central station roof, other parts are the CIS, facilitate inverse unearthed under the building’s roof.
2.4 station located in the central atrium
Station Hall in two central station escalator, stairs opened two 17.93mx8.26m holes, to withstand a hole on both sides of station Hall plate vertical loading except outside the side wall of the station, Kong Zhou located longitudinal beams, of horizontal beams and steel hanger rods. Transverse beams supporting column and in the station concourse, respectively on the longitudinal beams, vertical girder supporting in singling out horizontal beam and anchor on 50 steel hanger rods in the dark beams of the roof. Holes on both sides of station Hall itself as a horizontal beam under the station side wall the horizontal to the soil and water pressure, and on supporting plate in the holes at each end of the station Hall. No station Hall in the atrium of plate longitudinal beams, Atrium-in the column column.
2.5 protection of 110,000-volt cable lug design
Gang Xia station of 110,000-volt cable located in the East of the caitian road from caitian road center line crossing at the 30m of the pit. Root 200PVC embedded in 9 of the cable pipes, PVC pipes buried under the road after 890×1700 of C15 concrete fixed.
Steel trestle Bracket we use protection programmes to protect the 110,000-volt cable concrete blocks, both ends of the steel trestle abutment in lateral 5m of bearing platform of the station, under the CAP to two bored pile for Foundation of PHI 1000, end of bored pile to stroke of granite.
Steel trestle bridge is composed of angle steel space truss, high 3.5M, w 2.8M, long 30m. to avoid broken cables under blocks of concrete protection layer pouring cap beams, steel trestle-used to sink, top cap beam above the cable protection blocks. Made of steel trestle to the side on a two-pin beam of truss hoisting respectively in CAP, and truss rod be connected at the top. Concrete protection blocks using artificial interval under excavation, after every 1M excavators, immediately with a Bracket of 25 jacked protection blocks I-steel with high strength bolted in the side of the trestle bridge at both ends of bottom chord truss on a node Board. Bottom slash the steel trestle and within the abdomen stiffening rod, installation Bracket jacked connection, to form the complete space truss structure. Station construction has been completed, when the roof of Earth, masonry brick walls supporting trestle bridge of the bottom Bracket on the roof of concrete protection blocks and protection across a brick wall after the block the next time you fill sand cushion, demolition of steel trestle.
3, conclusion
Station structure design quite good to meet has Shenzhen City about sector and Metro company of requirements, especially implementation caitian road half site construction, and half site opening, will Metro construction on traffic of effect reduction to minimum degree; 110,000 v cable of in situ support supporting protection, greatly save has relocation of costs and blackout time, produced has huge of statistics and social benefit; station within suiting measures to local conditions to design has two a Atrium, this in national Metro design in the for first project, rich has station internal of space changes. In addition, Central station roof is a caitian road opening of full frame, speed up time, the use of reverse construction method of roof; side wall of the station using rectangular artificial Dig-hole pile of single-layer wall, which is also unique in the design of the Shenzhen Metro.