Influence of Strengthened Node Arrangement on Pull-Out Characteristics of Biaxial Geogrid

doi:10.16183/j.cnki.jsjtu.2019.275

Abstract

Abstract:

With the development of the geotechnical reinforcement technology, the form of reinforcing materials tends to be three-dimensional. Strengthened blocks of a certain thickness are attached to the joints of the longitudinal and transverse ribs of an ordinary biaxial geogrid so that it becomes a geogrid with strengthened nodes with a three-dimensional reinforcement effect. The layout of the strengthened nodes is divided into two types: upper and lower bilateral arrangement and upper unilateral arrangement, in which the total node thickness was the same. To explore the complex interaction mechanism of the reinforced soil interface, a series of indoor pull-out tests are conducted to investigate the influence of strengthened node arrangement on the characteristics of the reinforced soil interface. Based on the punching shear failure mechanism, the reinforcing mechanism of strengthened nodes is analyzed and the theoretical model of ultimate pull-out resistance is obtained. The results show that the ultimate pull-out resistance of the geogrid with strengthened nodes has a positive correlation with normal stress and node thickness. At the same normal stress, compared with the ordinary geogrid, the ultimate pull-out resistance of the two layout types of strengthened nodes is improved to some extent. The highest improvement rates are 118.33% and 96.73%, respectively. The interface apparent friction coefficient, pseudo cohesion, and comprehensive friction angle increase simultaneously. The ultimate pull-out resistance of the upper and lower bilateral arrangement is bigger than that of the upper unilateral arrangement. The error between the theoretical value based on the punching shear failure mode and the experimental value is less than 10%, and the strengthened node significantly improves the pull-out resistance of the geogrid.

Key words: geogrid, reinforcement, pull-out test, interface effect, ultimate pull-out resistance

CLC Number:

TU443

ZHANG Mengxi, MA Yuan, QIU Chengchun. Influence of Strengthened Node Arrangement on Pull-Out Characteristics of Biaxial Geogrid[J]. Journal of Shanghai Jiao Tong University, 2020, 54(12): 1307-1315.

Figures/Tables 12

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d/mm	质量占比/%
10～5	3.45
5～2	14.93
2～0.5	52.47
0.5～0.25	22.35
<0.25	6.80

工况	h₁/mm	h₂/mm	节点布置
1	0	0	无
2	3	0	上侧单侧
3	6	0	上侧单侧
4	3	3	上下双侧
5	9	0	上侧单侧
6	4.5	4.5	上下双侧

工况	c′/kPa	φ′/Pa	R²
1	11.23	12.37	1.000
2	12.37	15.09	0.995
3	19.71	15.70	0.999
4	21.73	16.89	1.000
5	25.08	16.90	1.000
6	27.78	17.39	0.991

工况	σ/kPa	T_r/N	R′
1	25	1 499.65	－
	50	2 005.99	－
	75	2 490.34	－
	100	2 983.40	－
2	25	1 667.37	11.18%
	50	2 396.68	19.48%
	75	2 951.63	18.52%
	100	3 505.02	17.48%
3	25	2 422.36	61.53%
	50	2 999.62	49.53%
	75	3 698.68	48.52%
	100	4 296.98	44.03%
4	25	2 649.41	76.67%
	50	3 310.15	65.01%
	75	3 998.6	60.57%
	100	4 697.89	57.47%
5	25	2 950.20	96.73%
	50	3 610.46	79.98%
	75	4 308.76	73.02%
	100	4 997.32	67.50%
6	25	3 274.15	118.33%
	50	3 848.70	91.86%
	75	4 525.93	81.74%
	100	5 396.85	80.90%

σ/kPa	工况	T_r试验值/N	T_rs		T_rb		T_sn		T_r理论值
σ/kPa	工况	T_r试验值/N	数值/N	比例/%	数值/N	比例/%	数值/N	比例/%	数值/N	误差/%
75	1	2 490.34	885.76	35.57%	1 451.46	58.28%	0	0.00%	2 337.22	6.15%
	2	2 951.63	885.76	30.01%	1 451.46	49.17%	769.32	26.06%	3 106.54	5.25%
	3	3 698.68	885.76	23.95%	1 451.46	39.24%	1 538.65	41.60%	3 875.87	4.79%
	4	3 998.60	885.76	22.15%	1 451.46	36.30%	1 692.51	42.33%	4 029.74	0.78%
	5	4 308.76	885.76	20.56%	1 451.46	33.69%	2 307.98	53.56%	4 645.20	7.81%
	6	4 525.93	885.76	19.57%	1 451.46	32.07%	2 538.77	56.09%	4 876.00	7.73%