Water Migration and Deformation Characteristics of Coastal Complex Strata in Artificial Freezing Process

doi:10.16183/j.cnki.jsjtu.2021.057

Abstract

Abstract:

The difference in the water migration and the deformation characteristics of silty sand and clay in the freezing process cannot be ignored when the artificial ground freezing method is used in coastal complex strata consisting of clay and silty sand, and is also the root cause of current engineering accidents caused by freezing. In order to find out the difference of the water migration and the deformation characteristics between the silty sand and clay, a self-made single side freezing instrument was used to conduct a series of freezing tests of original silty sand of ②₃ layer and the remodeled clay of ④ layer in Shanghai at a freezing temperature of -20 ℃, -15 ℃, and -10 ℃. The results show that the deformation curves can be divided into steep curve I(silty sand) and gradual curve II(clay). The deformation curves of different layers of clay soil sample fluctuated greatly with time. The results indicate that water migration is fully developed inside the clay during the freezing process, while most of the water inside the silty sand freeze quickly and thus water migration is not developed as obvious as that inside the clay. In addition, the deformation curves of the two types of soils is consistent with the distribution changes of water inside the silty sand and clay after freezing. Based on the research results, specific suggestions can be made for the relevant measures to deal with engineering problems such as frost heave in the practice of the freezing method for coastal complex strata consisted of silty sand and clay.

Key words: artificial ground freezing method, water migration, silty sand, clay

CLC Number:

TU111.2

ZHOU Jie, REN Junjie. Water Migration and Deformation Characteristics of Coastal Complex Strata in Artificial Freezing Process[J]. Journal of Shanghai Jiao Tong University, 2022, 56(5): 675-683.

Figures/Tables 11

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试验土样与指标	内摩擦角/(°)	黏聚力/kPa	重度/(kN·cm^-3)	含水率/ %	土粒比重
原状采集软黏土	11.5	14.0	16.90	49.86	2.69
试验用重塑软黏土	11.0	12.7	16.55	48.96	2.69
原状采集粉砂土	28.5	1.4	18.60	28.78	2.71
试验用原状粉砂土	28.3	1.4	18.61	28.69	2.71

试验编号	土样类型	冷端温度/℃
1	原状粉砂土	-10
2	原状粉砂土	-15
3	原状粉砂土	-20
4	重塑软黏土	-10
5	重塑软黏土	-15
6	重塑软黏土	-20

土样	冷端温度/℃	a	b	c	R²
粉砂土	-20	3.2185	0.0023	-11.1340	0.9937
粉砂土	-15	2.6785	0.0029	-10.2072	0.9961
粉砂土	-10	2.2085	0.0010	-8.5531	0.9975
软黏土	-20	1.8151	0.0069	-4.6629	0.9735
软黏土	-15	1.7139	0.0043	-4.2650	0.9924
软黏土	-10	1.7851	0.0035	-5.7038	0.9753