Numerical simulation study on the structural stability of lattice retaining wall for gas pipeline in mountainous area

Figure 1.

Figure 2.

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Interface parameters between gabion cages and the slope surface

Screen	Normal stiffness modulus kn/(k N·m-3)	Shear stiffness modulus kt/(k N·m-3)	cohesion c/k Pa	Angle of internal friction φ/(°)
Gabin cage - Slope	5.5×108	4.7×107	3.5	21.4
Gabion cage - Gabion cage	3.5×108	3.1×108	31	35.2

Stability coefficient and evaluation results of slope at each stage

Construction phase	Construction procedure	Stability coefficient F s	Evaluation result
1	Untimbering	1.29	Basically stable
2	Prestressed anchor cable and lattice beam support	1.56	Stable
3	Gabion cage excavation, step construction	1.86	Stable
4	Gabion cage support	1.67	Stable

Mechanical parameters of rock and soil mass and supporting structure

Name	Cell type	Modulus of elasticity E/M Pa	Poisson’s ratio μ	Heavy gamma γ/(k N·m-3)	Saturation weight γ sat/(k N·m-3)	Cohesion c/k Pa	Angle of internal friction φ/(°)
Fully weathered granite	Plane strain	25	0.305	20.8	22.3	5.5	35
Heavily weathered granite	Plane strain	550	0.266	25.5	26.4	56	36
Moderately weathered granite	Plane strain	19043	0.227	25.9	26.5	83	37
Anchor rope	The implantable truss	210006	0.302	77.5
Lattice beam	Beam	31007	0.203	25.2
Lattice network	Geotechnical grid	1404	0.301	25.6
Gubbin packing	Plane strain	2008	0.305	25.1	27.6	21	46

Influence of cohesive force of packing on horizontal displacement of wall

C/k Pa	C Rate of change/%	Single stage retaining wall D max/mm	Single stage retaining wall (d max/H)/%	Single stage retaining wall (d max/H)Rate of change/%
5	-50	61.20	0.766	+247.74
10	5	17.62	0.221	0
15	+50	7.49	0.095	-57.28
20	+100	4.01	0.048	-77.28
25	+150	3.28	0.042	-81.37
30	+200	3.30	0.042	-81.37