1 General Provisions
1.0.1 This code is formulated with a view to unifying the technical requirements for design and construction for diaphragm wall structure of port engineering, achieving advanced technology, economic rationality, safety and usability, and effectively controlling the engineering quality.
1.0.2 This code is applicable to the design and construction for quay and revetment diaphragm wall structure of port engineering and support diaphragm wall structure of foundation pit.
1.0.3 Design and construction for quay and revetment diaphragm wall structure of this code shall be used in combination with the current professional standard "Code for Design and Construction for Quay Wall of Sheet Pile" (JTJ 292).
1.0.4 As for the design and construction for diaphragm wall structure of port engineering, not only the requirements stipulated in this code, but also those in the current relevant ones of the nation shall be complied with.
2 Terms
2.0.1 Diaphragm wall
It refers to the continuously underground wall formed by concreting or inserting precast concrete member after the groove forming or hole forming with special machinery.
2.0.2 Front wall
It refers to the diaphragm wall at the riverside face in the quay and revetment engineering.
2.0.3 Anchor diaphragm wall
It refers to the diaphragm wall as the front wall anchor structure.
2.0.4 Capping beam
It refers to the concrete connecting beam set at the top of the diaphragm wall.
2.0.5 Guide beam
It refers to the continuous beam set at the end of the draw bar to make the entire front wall carry loads.
2.0.6 Breast wall
It refers to the cast-in-place concrete members set at the top of the front wall to combine capping beam and guide beam.
2.0.7 Draw bar
It refers to the connecting member between front wall and anchor member.
2.0.8 Soil bolt
It refers to the anchor structure combining reinforcement or steel strand and soil mass with cement mortar in the drilling holes inside the stable soil layer.
2.0.9 Waist beam
It refers to the continuous beam set at the end of the support or soil bolt to make the entire wall carry loads.
2.0.10 Ring beam
It refers to the annular connecting and supporting beam set on the circular diaphragm wall.
2.0.11 Vertical rib
It refers to the vertical connecting beam connecting the adjacent ring beam in the circular diaphragm wall structure.
3 Design for Quay and Revetment Diaphragm Wall Structure
3.1 Construction
3.1.1 Diaphragm wall may adopt cast-in-place or precast reinforced concrete structures. Cast-in-place diaphragm wall may adopt rectangular, T-shaped or drilling hole row-pile-shaped section, as shown in Figure 3.1.1. Precast diaphragm wall should adopt rectangular section.
Figure 3.1.1 Schematic diagram of diaphragm wall section shape
(a) Rectangular; (b) T-shaped; (c) Drilling hole row-pile-shaped
3.1.2 Section type and segment length of diaphragm wall shall be determined according to the load carrying conditions, construction conditions and environment conditions of the wall. Unit groove segment length of cast-in-place diaphragm wall may be 4~8m.
3.1.3 Soil-leakage-proof joint types or measures shall be adopted between the construction unit segments of quay and revetment front wall.
3.1.4 Diaphragm wall thickness or row pile diameter shall be determined by calculating with strength and crack width. Where the cast-in-place diaphragm wall is adopted as the front wall, its thickness should be 600~1300mm; where the cast-in-place diaphragm wall is adopted as the anchor structure, its thickness should be 600~1000mm.Row pile diameter should not be less than 550mm.Thickness of precast diaphragm wall should be 400~800 mm.
3.1.5 Design for the reinforced concrete of diaphragm wall shall meet the following requirements.
3.1.5.1 Concrete strength grade shall not be less than C25.
3.1.5.2 Protection layer thickness of main reinforcement shall not be less than 70mm.
3.1.5.3 Stressed reinforcement should be Grade I or Grade II, and its diameter shall not be less than 16mm.
3.1.5.4 Constructional reinforcement may be Grade I. Constructional reinforcement diameter of rectangular and trapezoidal cast-in-place diaphragm wall shall not be less than 12mm; constructional reinforcement diameter of drilling hole row-pile-shaped and precast diaphragm wall shall not be less than 8mm.
3.1.5.5 The subdivision length of cast-in-place diaphragm wall reinforcement cage shall be determined according to such factors as the length of unit groove segment, type of joint and capacity of hoisting equipment. The bottom of reinforcement cage should be properly narrowed in the thickness direction; gap of 100~200mm should be reserved between the reinforcement cage and wall bottom; the main reinforcement of reinforcement cage shall extrude the wall top and shall reserve sufficient length for anchorage . If the joint pipe joints are adopted, 150~200mm gap should be reserved between the side end and joint pipe.
3.1.5.6 Reinforcement configuration of cast-in-place diaphragm wall reinforcement cage shall not only meet the load carrying requirements of the structures under the design state but also shall meet the hoisting requirements.
