Negative Pore Water Pressure in Aquitard Enhances Land Subsidence: field, laboratory and numerical evidence

2021 ◽  
Author(s):  
Chun Liu ◽  
Bin Shi ◽  
Kai Gu ◽  
Tiansheng Zhang ◽  
Chaosheng Tang ◽  
...  
Keyword(s):  
Pore Water ◽  
Land Subsidence ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Numerical Evidence ◽  
Field Laboratory

scholarly journals Experimental study on mechanism for pumping-induced land subsidence

2020 ◽  
Vol 382 ◽  
pp. 387-390
Author(s):  
Yun Zhang ◽  
Guofeng He ◽  
Jichun Wu ◽  
Zhiduo Zhu ◽  
Xuexin Yan ◽  
...  
Keyword(s):  
Pore Water ◽  
Model Test ◽  
Land Subsidence ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Physical Model Test ◽  
Silty Clay ◽  
Sand Layer ◽  
Test Results ◽  
Clay Layers

Abstract. Groundwater pumping can cause severe land subsidence, yet the mechanisms have not been completely clear. A laboratory physical model test was done to investigate the mechanism for pumping-induced land subsidence. In the model test, a model well was installed and pumpage through the well was taken. During and after pumping, the soil displacement and the pore water pressure were documented. The pore water pressure within the pumped sand layer decreased immediately after pumping and recovered immediately after stopping pumping, while the pore water pressure in the neighboring silty clay layers first increased and then decreased with pumping, and first decreased and then increased after pumping was stopped and groundwater level in the sand layer recovered. The duration within which the pore water pressure in the silty clay increased when pumping was increasingly great with the distance from the pumped sand layer. The compaction of the neighboring silty clay first occurred near the interface between the silty and sand layers, and the silty clay expanded vertically within some zones. The test results indicate that the mechanism for land subsidence is complex. Due to their low permeability, aquitard units may expand in a period when groundwater is withdrawn from the neighboring aquifer units, and they may compact when groundwater is recharged into the neighboring aquifer units. This is one of the reasons for the lagging compaction of aquitard units.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

The temperature and pore water pressure in soil subjected to dynamic load

2018 ◽  
Vol 35 (2) ◽  
pp. 111
Author(s):  
Kun ZHANG ◽  
Ze ZHANG ◽  
Xiangyang SHI ◽  
Sihai LI ◽  
Donghui XIAO
Keyword(s):  
Pore Water ◽  
Dynamic Load ◽  
Pore Water Pressure ◽  
Water Pressure

Prediction of pore-water pressure response to rainfall using support vector regression

2016 ◽  
Vol 24 (7) ◽  
pp. 1821-1833 ◽  
Author(s):  
Nuraddeen Muhammad Babangida ◽  
Muhammad Raza Ul Mustafa ◽  
Khamaruzaman Wan Yusuf ◽  
Mohamed Hasnain Isa
Keyword(s):  
Support Vector Regression ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Pressure Response ◽  
Support Vector

scholarly journals Dilation of subglacial sediment governs incipient surge motion in glaciers with deformable beds

2020 ◽  
Vol 476 (2238) ◽  
pp. 20200033 ◽  
Author(s):  
B. M. Minchew ◽  
C. R. Meyer
Keyword(s):  
Pore Water ◽  
Flow Model ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slip Rate ◽  
Effective Pressure ◽  
Ice Flow ◽  
History Of ◽  
Glacier Surges ◽  
Geographical Clustering

Glacier surges are quasi-periodic episodes of rapid ice flow that arise from increases in slip rate at the ice–bed interface. The mechanisms that trigger and sustain surges are not well understood. Here, we develop a new model of incipient surge motion for glaciers underlain by sediments to explore how surges may arise from slip instabilities within a thin layer of saturated, deforming subglacial till. Our model represents the evolution of internal friction, porosity and pore water pressure within the till as functions of the rate and history of shear deformation, and couples the till mechanics to a simple ice-flow model. Changes in pore water pressure govern incipient surge motion, with less permeable till facilitating surging because dilation-driven reductions in pore water pressure slow the rate at which till tends towards a new steady state, thereby allowing time for the glacier to thin dynamically. The reduction of overburden (and thus effective) pressure at the bed caused by dynamic thinning of the glacier sustains surge acceleration in our model. The need for changes in both the hydromechanical properties of the till and the thickness of the glacier creates restrictive conditions for surge motion that are consistent with the rarity of surge-type glaciers and their geographical clustering.

Sign in / Sign up

Export Citation Format

Share Document