DOI: 10.5061/dryad.69p8cz8zm
title: Deformation of the clay layer and Fluxes at the bottom of the clay layer

description: A physical model test has been carried out to study the groundwater
 dynamics, water balance, and deformation characteristics of the aquitard
 in response to an abrupt hydraulic head decline in the adjacent confined
 aquifer. The hydraulic head in the clay layer is initially constant. The
 hydraulic head in the lower sand layer declines suddenly by φ  at
 the beginning and then remains unchanged during testing. We measured the
 drainage flux at the bottom of the aquifer and the subsidence of the clay
 layer.This supporting information document provides: (1)Supplementary
 Table 1 (Table S1), which presents time series data of the deformation of
 the clay layer (mm); (2) Supplementary Table 2 (Table S2), which gives
 time series data of the fluxes at the bottom of the clay layer (cm3/s).
description: The hydraulic head in the clay layer is initially constant. The
 hydraulic head in the lower sand layer declines suddenly by
 <i>φ</i>  at the beginning and then
 remains unchanged during testing. We measured the drainage flux at the
 bottom of the aquifer and the subsidence of the clay layer. The testing
 steps are given as follows: (1) Initial inspection of
 the testing device: The consolidation container must be ensured to be
 sealed, and the inlet and outlet pipes must not be obstructed. The testing
 instrument must be ensured to operate normally. (2)
 Soil sample preparation: Measure the weight of sand and clay with an
 electronic balance scale. The inner wall of the consolidation container is
 cleaned and smeared with a layer of grease or Vaseline; water is injected
 into the consolidation container through the overflow tank and the water
 table is raised slowly; no bubble is allowed in the filter layer during
 the water injection process; the consolidation container is successively
 filled with sand layer, clay layer, and sand layer, and the device to
 measure the settlement is placed at the top of and below the clay layer
 after each soil layer is consolidated under its self-weight for a duration
 of 24 hours. Turn off all the valves except the exhaust valve, and pump
 out the air in the container with a vacuum pump; increase the negative
 pressure within the consolidation container gradually at a given pressure
 sequence (e.g., − 0.02, − 0.04, − 0.06, − 0.08, and −0.1 MPa); the time
 interval for maintaining each pressure level is 12 hours.
 3) After the soil layers are saturated, water is added slowly to
 reach the target elevation; open the valve of the inlet pipe, and supply
 water into the device; mount the water supply tank at the designed height,
 and fill in it with water; discharge the excess water from the overflow
 nozzle; adjust the position of dial gauge, fasten it, and record the
 initial reading; observe the readings of the dial indicator until they do
 not vary. This process generally takes a few days. (4)
 Record the readings of the dial indicator during testing. Start the test
 by opening the valve of outlet pipe; decrease the hydraulic head below the
 confined soil layer by <i>φ</i>= 1 m at the beginning of test,
 and then maintain it to be constant; at the same time, record the readings
 of the dial indicator to calculate the deformation (<i>S</i>)
 of clay layer (Table S1) and measure the flux from the outlet of overflow
 tank using an electronic balance (the water discharge is held with a
 measuring cup on an electronic balance) to calculate the flux
 (<i>Q</i><sub>b</sub>) at the bottom of the clay
 layer (Table S2). Observe the readings continuously until they do not
 vary, and the test is then terminated; the observation duration is 480
 minutes; the flux becomes stable at the end of observation.