基于泥浆平衡地压的桩孔稳定性分析及支护建议

doi:10.16183/j.cnki.jsjtu.2018.330

摘要/Abstract

摘要：

基于泥浆压力平衡地压的原理,建立一种分析桩孔稳定的力学模型,分析无支护开挖、泥浆护壁成孔、硬支护成孔3种施工方式的应用条件与使用范围,给出无支护成孔最大深度、护壁泥浆下限容重的确定办法与实用表格.研究结果表明:土体的摩擦角、黏聚力与泥浆容重是维持桩孔稳定的基本要素;当成孔深度小于无支护成孔最大深度时,可采用无支护开挖,否则须采用泥浆护壁辅助成孔,且泥浆重度不得小于场地土要求的护壁泥浆下限容重;当摩擦角大于25°时,可任意选择泥浆重度;当查表计算所得的护壁泥浆下限容重大于规范给定的最大泥浆容重时,则需采用套管等硬支护措施.

关键词: 桩孔稳定, 护壁泥浆, 泥浆重度, 无支护临界深度

Abstract:

Based on the principle of mud pressure balance earth pressure, this paper establishes a mechanical model for analyzing the stability of pile hole, and analyzes the applicable conditions and application scopes of the three construction methods, namely, no-support excavation, the hole formation method by mud retaining wall, and the hole formation method by hard support. It also provides reasonable determination methods for maximum depth of pore-creating without support, lower limit value of mud weight of protecting wall, and useful tables. The research results show that the friction angle, the cohesion, and the mud weight of soil are basic factors for maintaining the stability of the pile hole. When the depth of pore-forming is less than the maximum depth of pore-creating without support, no-support excavation can be adopted. Otherwise, hole-forming should be assisted by slurry-support, and mud weight should not be less than the lower limit value of mud weight for the retaining wall determined by the site soil. When the friction angle is greater than 25°, mud weight can be arbitrarily selected. When the lower limit value of mud weight for the retaining wall calculated by look-up table is greater than the maximum mud weight given by specification, casing or other hard support measures should be adopted.

Key words: stability of pile hole, mud of protecting wall, mud weight, critical depth without support

中图分类号:

TU441.35

熊国军, 王建华, 陈锦剑. 基于泥浆平衡地压的桩孔稳定性分析及支护建议[J]. 上海交通大学学报, 2021, 55(9): 1108-1115.

XIONG Guojun, WANG Jianhua, CHEN Jinjian. Stability Analysis and Support Suggestions of Pile Hole Based on Mud Pressure Balance Earth Pressure[J]. Journal of Shanghai Jiao Tong University, 2021, 55(9): 1108-1115.

图/表 9

图1

表1

图2

图3

表2

不同摩擦角与相对黏聚力下的$\bar{z}_{cr}$

φ/ (°)	$z - cr$
φ/ (°)	c/(γR_A) =1	c/(γR_A) =2	c/(γR_A) =3	c/(γR_A) =4	c/(γR_A) =5	c/(γR_A) =6	c/(γR_A) =7	c/(γR_A) =8	c/(γR_A) =9	c/(γR_A) =10	c/(γR_A) =11	c/(γR_A) =12	c/(γR_A) =13	c/(γR_A) =14	c/(γR_A) =15
0	2.3	4.5	6.6	8.6	10.6	12.5	14.4	16.3	18.2	20.0	21.8	23.6	25.4	27.2	29.0
5	2.7	5.2	7.9	10.1	12.5	14.8	17.1	20.5	21.7	24.0	26.1	28.3	30.5	32.7	34.9
10	3.0	6.2	9.3	12.3	15.3	18.3	21.3	24.0	27.1	30.0	32.9	35.8	38.6	41.5	44.3
15	3.6	7.6	11.7	15.9	20.0	24.2	28.3	32.7	36.5	40.5	44.7	48.7	52.8	56.8	60.9
20	4.5	10.2	16.3	22.6	29.0	35.5	41.9	48.4	54.9	61.4	68.0	74.5	81.0	87.5	94.0
25	6.1	15.5	26.1	37.3	50.1	62.2	74.5	86.8	99.2	111.5	124.1	136.7	149.3	161.9	174.6
30	10.8	31.7	60.2	78.4	120.2	150.9	180.8	214.9	226.7	281.3	316.1	350.6	377.0	415.7	456.1
35	35.8	140.6	263.5	382.7	495.7	603.7	725.1	1036.9	1189.2	1341.7	∞	∞	∞	∞	∞
40	580.8	∞	∞	∞	∞	∞	∞	∞	∞	∞	∞	∞	∞	∞	∞

表2

图4

表3

不同摩擦角与相对黏聚力下的 γ - sw _ min

φ/(°)	$γ - sw_min$
φ/(°)	c/(γR_A) =1	c/(γR_A) =2	c/(γR_A) =3	c/(γR_A) =4	c/(γR_A) =5	c/(γR_A) =6	c/(γR_A) =7	c/(γR_A) =8	c/(γR_A) =9	c/(γR_A) =10	c/(γR_A) =11	c/(γR_A) =12	c/(γR_A) =13	c/(γR_A) =14	c/(γR_A) =15
0	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—
5	0.804	0.826	0.848	0.870	0.892	0.914	0.936	0.958	0.980	1.002	1.024	1.046	1.068	1.091	1.113
10	0.606	0.623	0.641	0.658	0.675	0.692	0.709	0.726	0.744	0.761	0.778	0.795	0.812	0.829	0.847
15	0.438	0.451	0.464	0.477	0.490	0.504	0.517	0.530	0.543	0.556	0.569	0.583	0.596	0.609	0.622
20	0.279	0.289	0.299	0.309	0.319	0.329	0.338	0.348	0.358	0.368	0.378	0.388	0.397	0.407	0.417
25	0.188	0.195	0.202	0.209	0.216	0.223	0.230	0.237	0.244	0.251	0.258	0.265	0.272	0.279	0.286
30	0.106	0.111	0.115	0.12	0.124	0.129	0.134	0.138	0.143	0.147	0.152	0.156	0.161	0.166	0.170
35	0.050	0.053	0.056	0.058	0.061	0.064	0.066	0.069	0.071	0.074	0.077	0.079	0.082	0.085	0.087

表3

图5

表4

不同摩擦角与相对黏聚力下的$\bar{z}_{max}$

φ/(°)	$z - max$
φ/(°)	c/(γR_A)=1	c/(γR_A)=2	c/(γR_A)=3	c/(γR_A)=4	c/(γR_A)=5	c/(γR_A)=6	c/(γR_A)=7	c/(γR_A)=8
0	7.5	14.2	20.5	26.7	32.7	38.7	44.6	50.6
5	28.6	58.8	88.0	116.5	144.6	172.5	200.2	227.7
φ/(°)	$z - max$
φ/(°)	c/(γR_A)=9	c/(γR_A)=10	c/(γR_A)=11	c/(γR_A)=12	c/(γR_A)=13	c/(γR_A)=14	c/(γR_A)=15	c/(γR_A)=16
0	56.4	62.3	68.2	74.0	79.9	85.8	91.6	—
5	255.1	282.4	309.6	336.9	363.8	390.7	417.2	—

表4

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φ/(°)	l_γ	m_γ	n_γ	l_q	m_q	n_q
0	0	1	0	0.9765	0.0002	0
5	0.1049	0.9307	-0.0004	0.9410	0.0023	-0.0000
10	0.2588	0.8366	-0.0011	0.8996	0.0043	-0.0001
15	0.4425	0.7208	-0.0019	0.8511	0.0060	-0.0001
20	0.6857	0.5499	-0.0029	0.7945	0.0073	-0.0001
25	0.8151	0.4470	-0.0031	0.7290	0.0080	-0.0001
30	0.9475	0.3050	-0.0030	0.6537	0.0079	-0.0001
35	0.9879	0.1761	-0.0024	0.5684	0.0068	-0.0001