Hydro-mechanical coupled analyses on wall deformations caused by deep excavations and dewatering in a confined aquifer

2021 ◽  
Author(s):  
Chen-Xin Peng ◽  
Nian-Wu Liu ◽  
Ming-Guang Li ◽  
Liang Zhen ◽  
Jin-Jian Chen
2017 ◽  
Author(s):  
Pascalia Vinca Alvando ◽  
Achmad Darul ◽  
Dasapta Erwin Irawan

Airtanah merupakan salah satu faktor penting yang berkontribusi terhadap ketidakstabilan lereng, air akan mengisi pori tanah sehingga tekanan air pori meningkat. Pada tahun 2009 di Pit E, PT. BC khususnya low wall pernah terjadi longsor, tujuan penelitian ini untuk mengetahui besar penurunan muka airtanah (drawdown) serta melakukan simulasi dalam waktu 8 tahun kedepan setelah upaya dewatering pada tahun 2016 dengan menggunakan sistem drain hole yang dipasang secara inclined. Model konseptual daerah penelitian dibangun dengan data pengamatan muka airtanah mula-mula, curah hujan, topografi dan properti hidrogeologi yang ditentukan berdasarkan asumsi teoriritis. Simulasi numerik menggunakan metode beda hingga dilakukan dalam dua skenario yaitu pada tiga IDH aktif dan penambahan tiga IDH di luar model pada akuifer terkekang dengan variasi kedalaman 50 m dan 80 m. Drawdown hasil simulasi kemudian dikalibrasi dengan perhitungan metode Theis. Hasil studi menunjukan nilai drawdown dari perhitungan Theis lebih kecil dari hasil simulasi numerik. Outflow pada pemodelan juga menghasilkan nilai yang lebih besar dari pengamatan di lapangan. Parameter adjustment berupa nilai konduktivitas hidraulik kemudian dilakukan untuk mengetahui pengaruhnya terhadap besar drawdown. Hasilnya menunjukan bahwa nilai konduktivitas hidraulik memiliki pengaruh yang signifikan terhadap perubahan besar drawdown. (Pre-print)Kata kunci: drawdown, confined aquifer, inclined drain hole, dewatering


2017 ◽  
Vol 54 (1) ◽  
pp. 15-32
Author(s):  
Theresa Jehn-Dellaport ◽  
Tammi Renninger

A partially defined and largely unexplored confined aquifer in Colorado, Nebraska, and Wyoming is identified regionally through interpretation of geophysical logs, well drilling, coring, petrographic analysis, and GIS interpretation. The aquifer is a fine-grained arkosic sandstone, with thickness ranging up to 1000 ft in some areas. The aquifer represents a significant water resource for ranching and other development in northeastern Colorado and may be a resource for Wyoming, and Nebraska. Nomenclature for this aquifer is suggested. Water wells penetrating the entire aquifer have produced up to 200 gpm. Water quality data is presented including total dissolved solids, boron, and microbial methane.


Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1952
Author(s):  
Subrata Halder ◽  
Lingaraj Dhal ◽  
Madan K. Jha

Providing sustainable water supply for domestic needs and irrigated agriculture is one of the most significant challenges for the current century. This challenge is more daunting in coastal regions. Groundwater plays a pivotal role in addressing this challenge and hence, it is under growing stress in several parts of the world. To address this challenge, a proper understanding of groundwater characteristics in an area is essential. In this study, spatio-temporal analyses of pre-monsoon and post-monsoon groundwater-levels of two coastal aquifer systems (upper leaky confined and underlying confined) were carried out in Purba Medinipur District, West Bengal, India. Trend analysis of seasonal groundwater-levels of the two aquifers systems was also performed using Mann-Kendall test, Linear Regression test, and Innovative Trend test. Finally, the status of seawater intrusion in the two aquifers was evaluated using available groundwater-quality data of Chloride (Cl−) and Total Dissolve Solids (TDS). Considerable spatial and temporal variability was found in the seasonal groundwater-levels of the two aquifers. Further, decreasing trends were spotted in the pre-monsoon and post-monsoon groundwater-level time series of the leaky confined and confined aquifers, except pre-monsoon groundwater-levels in Contai-I and Deshpran blocks, and the post-monsoon groundwater-level in Ramnagar-I block for the leaky confined aquifer. The leaky confined aquifer in Contai-I, Contai-III, and Deshpran blocks and the confined aquifer in Nandigram-I and Nandigram-II blocks are vulnerable to seawater intrusion. There is an urgent need for the real-time monitoring of groundwater-levels and groundwater quality in both the aquifer systems, which can ensure efficient management of coastal groundwater reserves.


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