Combination of stress-controlled erosion and tensile failures during development of piping conduits in locked sand

2020 ◽  
Author(s):  
Jan Vojtisek ◽  
Jiri Bruthans ◽  
Martin Slavik
Keyword(s):  
Water Flow ◽  
Water Table ◽  
Field Experiments ◽  
Ground Surface ◽  
Empty Space ◽  
Fracture Zones ◽  
Transversal Section ◽  
Erosion Mechanisms ◽  
Fast Flow ◽  
Locked Sand

<p>Piping is an erosion process in which cracks and macropores extend into channels with a diameter of cm or more. This process is important for the formation of highly permeable porosity, failure of the levees, formation of gullies and intense erosion of agricultural soil. In this research we studied the evolution of conduits in Střeleč locked sand (SLS). This material composes mainly of quartz and resembles friable sandstone. Study was done in Střeleč quarry (Czech Republic), where depression in the regional water table (decrease of water table by ~20 m) due to the water pumping causes fast flow (up to 40 cm/s) through fractures in the SLS body. Large conduit systems developed along fracture zones that divide the SLS body into subvertical blocks with a width of cm to tens of cm in each fracture zone. Erosion starts at water table and blocks bordered by fractures are eroded by the fast water flow, especially the parts that are in stress shadows due to inefficient loading from the surrounding sandstone mass. Blocks whose base is eroded tend to collapse, which leads to the creation of free space above the water table and also possibly destabilization of the sides. Empty space propagates upward mostly meters but sometimes tens of meters toward ground surface. Experiments showed that the SLS is prone to erosion when it is under low gravity induced stress. In addition to observation of the existing conduits, the experiments focused on the evolution of transversal section of conduits in SLS were performed. Experimental erosion was done on fracture systems exposed in quarry by the flow of water from the hose. Sequence of photos of fracture zones evolving into conduit during experiments was taken and the evolution of the transverse section of conduits was observed. By this method the blocks were eroded to a depth of several decimeters. Based on field experiments and time-laps photos two erosion mechanisms are responsible for conduits evolution. While the less thick blocks are eroded mainly by rapid water flow, thicker blocks are eroded by tension failures (gravity driven wasting). The tension failure dominates, forming about 65 % of total erosion.</p><p>Many thanks to the management of Střeleč Quarry for enabling of the field documentation and experiments. The research was supported by Charles University Grant Agency (GAUK #1292119).</p>

LINKFLOW, A WATER FLOW COMPUTER MODEL FOR WATER TABLE MANAGEMENT: PART 3. MODEL APPLICATION

1997 ◽  
Vol 40 (6) ◽  
pp. 1543-1547 ◽  
Author(s):  
P. L. Havard ◽  
S. O. Prasher ◽  
R. B. Bonnell ◽  
A. Madani
Keyword(s):  
Water Flow ◽  
Water Table ◽  
Computer Model ◽  
Model Application ◽  
Water Table Management

Investigation of the Internal Blowout Accident Involving Overpressured Reservoirs: Case of CI-11 Well, Southern Tunisia

2021 ◽  
pp. 1-14
Author(s):  
Chaouki Khalfi ◽  
Riadh Ahmadi
Keyword(s):  
Water Flow ◽  
Water Table ◽  
Action Plan ◽  
Oil Field ◽  
Hot Water ◽  
Shallow Water Table ◽  
Ecological Consequences ◽  
Southern Tunisia ◽  
Drilling Operations ◽  
Recovery Program

Summary This study consists of an assessment of the ecological accident implicating the Continental Intercalaire-11 (CI-11) water well located in Jemna oasis, southern Tunisia. The CI-11 ecological accident manifested in 2014 with a local increase of the complex terminal (CT) shallow water table salinity and temperature. Then, this phenomenon started to spread over the region of Jemna, progressively implicating farther wells. The first investigation task consisted of logging the CI-11 well. The results revealed an impairment of the casing and cement of a huge part of the 9⅝ in. production casing. Historical production records show that the problems seem to have started in 1996 when a sudden production loss rate occurred. These deficiencies led to the CI mass-water flowing behind the casing from the CI to the CT aquifers. This ecological accident is technically called internal blowout, where water flows from the overpressurized CI groundwater to the shallower CT groundwater. Indeed, the upward CI hot-water flow dissolved salts from the encountered evaporite-rich formations of the Lower Senonian series, which complicated the ecological consequences of the accident. From the first signs of serious water degradation in 2014 through the end of 2018, several attempts have been made to regain control of annular upward water flow. However, the final CT groundwater parameters indicate that the problem is not properly fixed and communication between the two involved aquifers still persists. This accident is similar to the OKN-32 case that occurred in the Berkaoui oil field, southern Algeria, in 1986, and included the same CI and CT aquifers. Furthermore, many witnesses claim that other accidental communications are probably occurring in numerous deep-drilled wells in this region. Concludingly, Jemna CI-11, Berkaoui OKN-32, and probably many other similar accident cases could be developing regional ecological disasters by massive water resource losses. The actual situation is far from being under control and the water contamination risk remains very high. In both accidents, the cement bond failure and the choice of the casing point are the main causes of the internal blowout. Therefore, we recommend (1) a regional investigation and risk assessment plan that might offer better tools to predict and detect earlier wellbore isolation issues and (2) special attention to the cement bond settlement, evaluation, and preventative logging for existing wells to ensure effective sealing between the two vulnerable water table resources. Besides, in the CI-11 well accident, the recovery program was not efficient and there was no clear action plan. This increased the risk of action failure or time waste to regain control of the well. Consequently, we suggest preparing a clear and efficient action plan for such accidents to reduce the ecological consequences. This requires further technical detailed study of drilling operations and establishment of a suitable equipment/action plan to handle blowout and annular production accidents.

scholarly journals Experimental observation on laterally loaded pile in unsaturated silty soil

2019 ◽  
Vol 56 (11) ◽  
pp. 1545-1556 ◽  
Author(s):  
L.M. Lalicata ◽  
A. Desideri ◽  
F. Casini ◽  
L. Thorel
Keyword(s):  
Water Table ◽  
Ground Surface ◽  
Bending Moment ◽  
Data Interpretation ◽  
Partial Saturation ◽  
Laterally Loaded Piles ◽  
Silty Soil ◽  
Centrifuge Tests ◽  
Surface Data ◽  
Laterally Loaded

An experimental study was carried out to investigate the effects of soil partial saturation on the behaviour of laterally loaded piles. The proposed study was conducted by means of centrifuge tests at 100g, where a single vertical pile was subjected to a combination of static horizontal load and bending moment. The study was conducted on a silty soil characterized with laboratory testing under saturated and unsaturated conditions. During flight, two different positions of water table were explored. The influence of density was investigated by compacting the sample with two different void ratios. Finally, the effects of a variation of saturation degree on the pile response under loading were studied by raising the water table to the ground surface. Data interpretation allows drawing different considerations on the effects of partial saturation on the behaviour of laterally loaded piles. As expected, compared to saturated soils, partial saturation always leads to a stiffer and resistant response of the system. However, the depth of the maximum bending moment is related to the position of the water table and the bounding effects induced by partial saturation appear to be more important for loose soils.

scholarly journals Exploring the use of a column model for the characterization of microphysical processes in warm rain: results from a homogeneous rainshaft model

2007 ◽  
Vol 10 ◽  
pp. 145-152 ◽  
Author(s):  
O. P. Prat ◽  
A. P. Barros
Keyword(s):  
Field Experiments ◽  
Ground Surface ◽  
Cloud Base ◽  
Column Model ◽  
Raindrop Size Distribution ◽  
State Boundary ◽  
Raindrop Size ◽  
Microphysical Processes ◽  
Rain Events ◽  
Rain Rates

Abstract. A study of the evolution of raindrop spectra (raindrop size distribution, DSD) between cloud base and the ground surface was conducted using a column model of stochastic coalescense-breakup dynamics. Numerical results show that, under steady-state boundary conditions (i.e. constant rainfall rate and DSD at the top of the rainshaft), the equilibrium DSD is achieved only for high rain rates produced by midlevel or higher clouds and after long simulation times (~30 min or greater). Because these conditions are not typical of most rainfall, the results suggest that the theoretical equilibrium DSD might not be attainable for the duration of individual rain events, and thus DSD observations from field experiments should be analyzed conditional on the specific storm environment under which they were obtained.

scholarly journals Measurement of xylem water pressure using High-Capacity Tensiometer and benchmarking against Pressure Chamber and Thermocouple Psychrometer

2020 ◽  
Vol 195 ◽  
pp. 03014
Author(s):  
Roberta Dainese ◽  
Giuseppe Tedeschi ◽  
Thierry Fourcaud ◽  
Alessandro Tarantino
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
High Capacity ◽  
Ground Surface ◽  
Pressure Chamber ◽  
Rainwater Infiltration ◽  
Thermocouple Psychrometer ◽  
Earth Structures ◽  
Pressure Water ◽  
The Stability

The response of the shallow portion of the ground (vadose zone) and of earth structures is affected by the interaction with the atmosphere. Rainwater infiltration and evapotranspiration affect the stability of man-made and natural slopes and cause shallow foundations and embankments to settle and heave. Very frequently, the ground surface is covered by vegetation and, as a result, transpiration plays a major role in ground-atmosphere interaction. The soil, the plant, and the atmosphere form a continuous hydraulic system, which is referred to as Soil-Plant-Atmosphere Continuum (SPAC). The SPAC actually represents the ‘boundary condition’ of the geotechnical water flow problem. Water flow in soil and plant takes place because of gradients in hydraulic head triggered by the negative water pressure (water tension) generated in the leaf stomata. To study the response of the SPAC, (negative) water pressure needs to be measured not only in the soil but also in the plant. The paper presents a novel technique to measure the xylem water pressure based on the use of the High-Capacity Tensiometer (HCT), which is benchmarked against conventional techniques for xylem water pressure measurements, i.e. the Pressure Chamber (PC) and the Thermocouple Psychrometer (TP).

scholarly journals Performance of Global Atmospheric Datasets towards Groundwater Management

10.29007/5swr ◽  
2018 ◽  
Author(s):  
Paolina Bongioannini Cerlini ◽  
Silvia Meniconi ◽  
Bruno Brunone
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Groundwater Management ◽  
Water Flow ◽  
Water Table ◽  
Soil Moisture Content ◽  
Weather Forecasts ◽  
Reliable Tool ◽  
Umbria Region ◽  
Medium Range

With the aim of refining a reliable tool for groundwater management, the ERA-Interim and ERA5 global atmospheric datasets provided by the European Centre for Medium- Range Weather Forecasts (ECMWF) are examined. Attention is focused on the analysis of the behavior of the soil moisture content. The performance of ERA-Interim and ERA5 is evaluated by considering the water table measurements at three sites in the Umbria region as well as the dynamics of water flow towards the groundwater.

Communication and ‘Forestructures’ at the Geological Intersection of Caves and Subsurface Water Flow: Hermeneutics and Parochialism

2011 ◽  
Vol 30 (1) ◽  
pp. 85-105 ◽  
Author(s):  
Lee Florea ◽  
H. Vacher
Keyword(s):  
Water Flow ◽  
Water Table ◽  
Subsurface Water ◽  
Weight Of Evidence ◽  
Karst Aquifers ◽  
Hermeneutic Circle ◽  
Half Century ◽  
The Past ◽  
Past Half Century ◽  
Past Half

The direction of cave and karst science throughout its history has been partly determined by communication—or, more commonly, the lack of communication—between non-scientist cavers and non-caving physical geologists writing about karst. Within each community, advancement of ‘cave awareness’ occurred through a hermeneutic circle in which ‘forestructures’ guided progress. One result was regionalism of speleo-genetic theories developed within karst science because of the weight of evidence placed upon local or regional observations. Many speleogenetic theories of the mid-1900s suffer from this parochialism, failing to take into account findings from karst of different geologic settings. During the past half-century, the accumulated worldwide data on caves and karst suggest larger, more encompassing theories of speleogenesis. One such example of how speleogenetic theories have changed, partly explored in this essay, is the relation of cave formation to the position of the water-table. In many karst aquifers, including but not limited to alpine systems, one modern view envisions the enlargement of caves to proceed in a punctuated manner, driven by floods.

SOIL TRAFFICABILITY IN SPRING 1. SIMULATION OF THE DRAINAGE PROCESS

1983 ◽  
Vol 63 (1) ◽  
pp. 15-26
Author(s):  
C. L. PAUL ◽  
J. DE VRIES
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Water Table ◽  
Flow Characteristic ◽  
Transient State ◽  
Matric Potential ◽  
Flow Parameters ◽  
Ultimate Objective ◽  
Fraser Valley ◽  
Measured Water

A mathematical-physical model developed in the Netherlands for the simulation on nonsteady flow of water in subsurface-drained soils was tested by comparing its output with data collected in spring from two farmers’ fields in the Lower Fraser Valley of British Columbia. The ultimate objective of the tests was the prediction of soil strength and trafficability. The model was found to be useful for predicting depth to the water table and, to a lesser extent, soil water matric potential in the top 15 cm in fields drained by drains spaced at 30.5 m and 15.2 m. However, there were problems in evaluating input data. One problem was that of obtaining the drainage intensity, which was found to have a great effect on model output. A solution of the modified Glover-Dumm transient-state drainage equation provided a means of obtaining the drainage intensity directly from measured water table recession. A second problem was related to the use in the model of soil water flow parameters obtained from the water flow characteristic measured on undisturbed columns in the laboratory. Key words: Drainage model, matric potential, water table depth, trafficability, drainage intensity

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