Knowledge Center

At Cengrs, one of our core values is sharing of knowledge. Owing to our extensive experience in providing expert Geo-technical engineering services to the construction industry, we have over the years, gained significant knowledge about the key issues and challenges in this domain. To consolidate this valuable learning, we have established a Knowledge Centre, which primarily works on the theology of collating information & experiences, and disseminating it to interested organizations & individuals.

Through case studies and technical papers, our Knowledge Centre aims to serve as an excellent resource for anyone conducting Geo-technical activities. We strongly believe that this knowledge should be constantly refreshed and improved to provide companies with the required guidance & support for enhancing business processes and improving efficiency.

TECHNICAL PAPERS
Dynamic Compaction to Mitigate Liquefaction Potential
Sanjay Gupta, Ravi Sundaram & Sorabh Gupta, 11-Oct-2010

Abstract: At a project site in Greater Noida (U.P.), loose to medium dense ‘clean’ Yamuna sands were encountered, which were found to be susceptible to liquefaction to about 8-12 m depth. Dynamic compaction was carried out across the entire site to densify the soils and mitigate the risk of liquefaction. Field tests (including standard penetration tests and static cone penetration tests) carried out before and after dynamic compaction indicated that the ground improvement has been successful to the desired depth. Open foundations bearing on the improved ground could now be provided in place of piles, resulting in enormous cost-saving for the owner.

Citation : Sanjay Gupta, Ravi Sundaram, Sorabh Gupta (2010), “Dynamic Compaction to Mitigate Liquefaction Potential”, Proceedings, Indian Geotechnical Conference (IGC-2010), Mumbai, Volume-II, pp 783-786.

Performance of a Large Diameter Oil Storage Tank on Improved Clay Deposit
Gopal Ranjan, Ravi Sundaram and Sanjay Gupta, 02-Sep-2009

Abstract:Large diameter cylindrical welded steel tanks bearing on soft clay deposits can experience substantial settlement. Ground improvement by provision of granular piles is an effective method to strengthen the soft clay and control settlements within acceptable limits. The paper presents the installation technique together with results of load tests conducted on trial granular piles to assess the behavior of the improved ground. The tank performance, evaluated by hydro-testing the tank, compared well with the theoretical model used to compute the settlement of the improved ground

Citation :Gopal Ranjan, Ravi Sundaram and Sanjay Gupta (2009), Performance of a Large Diameter Oil Storage Tank on Improved Clay Deposit, Proceedings, 17th International Conference on Soil Mechanics & Geotechnical Engineering (17th ICSMGE-2009), Alexandria, Egypt.

Liquefaction Susceptibility Study at Commonwealth Games Village Delhi
Sanjay Gupta, Ravi Sundaram, Sorabh Gupta and G.V. Ramana G.V. Ramana Department of Civil Engineering, Indian Institute of Technology, Delhi, 03-Sep-2008

Abstract: Geotechnical investigations were carried out at the site of the Commonwealth Games-2010 Village site near Akshardham in New Delhi. The study included Spectral analysis of Surface Waves (SASW) tests conducted in conjunction with boreholes and static cone penetration tests to assess the liquefaction susceptibility during earthquakes. Detailed liquefaction susceptibility studies confirmed that soils to a depth of about 9.5 m are susceptible to liquefaction hazard. The paper discusses the approach used for the analysis together with the foundation system adopted.

Citation : Sanjay Gupta, Ravi Sundaram, Sorabh Gupta and G.V. Ramana (2008), Liquefaction Susceptibility Study at Commonwealth Games Village Delhi, Proceedings, Indian Geotechnical Conference (IGC-2008), Bangalore, Volume-II, pp 436-440.

Pump-out Tests in Alluvial Sands-A Case Study
Sorabh Gupta, Sanjay Gupta and Ravi Sundaram, 04-Sep-2008

Abstract: For design of the dewatering system for construction of a multi-storeyed building with three basements, pump-out tests were conducted to evaluate the various hydraulic parameters of the aquifer. The deposits at site consist of fine sands of alluvial origin. The test results indicated very high permeability of the aquifer, necessitating a complex dewatering system that was not envisaged earlier. The paper presents details of the test conducted and analysis of the test results.

Citation : Sorabh Gupta, Sanjay Gupta and Ravi Sundaram (2008), Pump-out Tests in Alluvial Sands – A Case Study, Proceedings, 6th Asian Young Geotechnical Engineers Conference (AYGEC)-2008, Bangalore, pp 47-54.

Pile Integrity Testing for Monitoring Pile Construction
Sanjay Gupta, Ravi Sundaram and Sorabh Gupta, 02-Nov-2008

Abstract: Low-strain Pile Integrity Testing (PIT) is a valuable, low-cost tool to locate major defects in, and estimate pile lengths of, bored and driven piles installed on site. It can serve to enhance the confidence level of the engineer on the quality of piles installed. The paper discusses the test procedure and limitations, and illustrates field results of low strain integrity tests performed on RCC bored cast-in-situ piles on infrastructure projects.

Citation : Sanjay Gupta, Ravi Sundaram and Sorabh Gupta (2008), Pile Integrity Testing for Monitoring Pile Construction, Proceedings, National Symposium on Geoenvironment, Geohazards, Geosynthetics and Ground Improvement-Experiences and Practices (4G) Indian Geotechnical Society (Delhi Chapter) pp 173-178.

Geotechnical Characterization of Dune Sands of the Thar Desert
Sanjay Gupta and Ravi Sundaram, 03-Sep-2007

Abstract: The aeolian sands of the Thar Desert are meta-stable in nature and experience volume change on contact with water even without application of load. The construction of a major power plant with heavily loaded statically and dynamically loaded facilities on such deposits requires a thorough appreciation of the engineering behavior of dune sands. The paper documents the detailed geotechnical investigations conducted for the project. Highlights of the results include -\n\n(i) the poorly graded sands have predominantly one particle size, \n(ii) SPT values are influenced by the overburden pressure, \n(iii) the dry sands have high electrical resistivity \n(iv) settlement increase of open foundations upon saturation is nearly 2.8 times, and \n(v) poor dynamic response of the collapsible sands is observed at shallow depths with two peak

Citation : Sanjay Gupta and Ravi Sundaram (2007), Geotechnical Characterization of Dune Sands of the Thar Desert, Proceedings, 13th Asian Regional Conference on Soil Mechanics & Geotechnical Engineering (13th ARC-2007), Kolkata, Volume-I, pp 204-207

Dynamic Characteristics of Alluvial Deposits-A case Study
Sanjay Gupta, Ravi Sundaram and Anurag Goyal, 02-Nov-2006

Abstract: The dynamic behavior of alluvial deposits of the Indo-Gangetic Alluvium depends primarily on the soil type, density and compactness. The paper presents results of cross-hole seismic tests and seismic refraction tests conducted at a power plant site in Haryana. The borehole and static cone penetration test data have been correlated to the P-wave and S-wave velocities to generate a geophysical model of the site conditions. From the test results, a four-layer model has been established for the project site.\n

Citation :  Sanjay Gupta, Ravi Sundaram and Anurag Goyal (2006), Dynamic Characteristics of Alluvial Deposits-A case Study, Proceedings, Geotechnical Engineering-Indian Experience (IGC-2006), Chennai, Volume-II, pp 827-830.

Mitigating Foundation Distress
Sanjay Gupta and Ravi Sundaram, 04-Sep-2005

Abstract: Mitigation of foundation distress deals with the science and art of saving foundations from distress or failure. Foundation distress refers to serviceability failure or may cause failure during the life of the structure. The approach for mitigating foundation distress is similar to that of Forensic Geotechnical Engineering, without involving court of law. Evaluation of what went wrong and why (the 4W’s) is the key to solve the problem and develop appropriate foundation rehabilitation system. The paper presents three case studies demonstrating the approach. In the cases presented, the ultimate failure had not taken place but distress in foundation had affected serviceability criteria and/or resulted in reduction in desired factor of safety. \n

Citation : Sanjay Gupta and Ravi Sundaram (2005), (Key Note, Expert Lecture) Mitigating Foundation Distress, Proceedings, Geotechnical Practices for Environmental Management, Disaster Mitigation and Foundation Engineering (IGC-2005), Ahmedabad, Volume-I, pp 95-102.

Deep Excavation Adjacent to a Multi-Storeyed Building Lateral Support
Sanjay Gupta, Ravi Sundaram and Pushpendra Singh, 05-Sep-2005

Abstract: To ensure safety of a tall multi-storeyed building adjacent to a deep excavation, cement grouting was done. The paper explains the site conditions and the scheme adopted. The grouting assisted in restraining lateral soil movement. Field observations confirmed that no soil movement occurred till the time the basement wall was constructed up to ground level.

Citation : Sanjay Gupta, Ravi Sundaram and Pushpendra Singh (2005), Deep Excavation Adjacent to a Multi-Storeyed Building Lateral Support, Proceedings, Geotechnical Practices for Environmental Management, Disaster Mitigation and Foundation Engineering (IGC-2005), Ahmedabad, Volume-II, pp 319-322.

Geotechnical Investigations: Dune Sands of the Thar Desert
Sanjay Gupta & Ravi Sundaram, 08-Nov-2004

Synopsis:The dune sands of the Thar Desert are meta-stable in nature and experience volume change on contact with water even without application of load. The construction of a major power plant on such deposits requires a thorough appreciation of the engineering behavior of dune sands. Geotechnical Investigation programme for major projects need to be framed based upon the geology of the area and characteristics of the deposits. The paper documents the detailed geotechnical investigations conducted for the project. Highlights of the results include (i) SPT values are influenced by the overburden pressure, (ii) settlement increase of open foundations upon saturation is nearly 2.8 times, and (iii) poor dynamic response of the collapsible sands is observed at shallow depths with two peaks in the frequency versus amplitude relationship – indicating collapsible structure.

Citation : Sanjay Gupta and Ravi Sundaram (2004), Geotechnical Investigations : Dune Sands of the Thar Desert, Proceedings, Ground Engineering : Emerging Techniques (GREET) (IGC-2004), Warangal, Volume-II, pp 1-9.

In-situ Testing Current Trends in Geotechnical Investigations
Sanjay Gupta and Ravi Sundaram, 21-Nov-2003

Abstract: The new emerging trend in modern geotechnical investigation is to place a greater emphasis on in-situ tests. These tests can be effectively used to predict foundation behaviour with a higher factor of reliability. The paper presents four different types of advanced in-situ testing techniques with three case histories to demonstrate effective use of such advanced in-situ tests – static cone penetration tests, pressuremeter tests, geophysical tests.\n

Citation : Sanjay Gupta and Ravi Sundaram (2003), (Key Note Lecture)In-situ Testing – Current Trends in Geotechnical Investigations, Proceedings, Geotechnical Engineering for Infrastructural Development (IGC-2003), Roorkee, Volume-II, pp 635-645.

Geotechnics of Artesian Flow Case Study of River Shivganga, Nepal
Sanjay Gupta & Ravi Sundaram, 03-Oct-2003

Abstract: Geotechnical investigations done for the bridge across River Shivganga on the Kohalpur-Mahakali Highway in the Terai region of southwestern Nepal reveal the occurrence of multiple layers at different depths with artesian ground water flow. The concept for foundation design in such strata should consider three aspects – (a) bed boiling (quick condition) should not develop even if maximum scour occurs, (b) during construction, a minimum soil cushion thickness should be available between foundation level and strata with artesian flow, and (c) for long term stability, the bearing capacity at artesian level should be computed using effective stress principle. The application of these concepts to fix the founding levels for well foundations for the bridge is discussed

Citation :  Ravi Sundaram and Sanjay Gupta (2003), Geotechnics of Artesian Flow – Case Study of River Shivganga, Nepal, Proceedings, 12th Asian Regional Conference on Soil Mechanics & Geotechnical Engineering (12th ARC-2003), Singapore, Volume-I, pp 603-606.

Foundation Stabilization of the Janmabhoomi Temple at Mangarh
Ravi Sundaram and Sanjay Gupta, 05-Sep-2003

Synopsis: The Janmabhoomi Temple is planned as an elegant structure in granite stone blocks. The foundation block bearing at 3 m depth is a 5.4 m thick massive platform made of granite masonry. Review of the soil condition revealed that under the design loads, the total and differential settlement may be excessive. To stabilize the foundation system, confinement of the foundation block was done by providing a row of 400 mm diameter closely spaced piles all around the Garba Griha, and in the central Mandap portion. Ground improvement was done in the associated structures (small temples corridor) to strengthen the soils and to restrict settlement.

Citation : Ravi Sundaram and Sanjay Gupta (2003), Foundation Stabilization of the Janmabhoomi Temple at Mangarh, Proceedings, Forensic Geotechnical Engineering Chennai, pp 168-172.

Dynamic Properties of Delhi Silt from Field Investigations
H. Rao, S.Gupta, S. Narasaiah and G.V. Ramana (2002), 25-Jun-2002
Abstract: \nAll the earthquake resistant design and analysis procedures require site-specific/local dynamic site characterization. Dynamic site characterization includes shear wave velocity profile with depth, modulus reduction curves and damping characteristics of local soils. These are very essential and basic parameters required to conduct local site response/seismic wave propagation studies that should be duly incorporated into any earthquake resistant deign/analysis. \n \nShear wave velocity profiling is not a routine geotechnical investigation activity, as very specialized methods like seismic reflection, refraction, seismic cross-hole, down-hole and steady state vibration tests which fall under the domain of geophysical methods, are required which are very time consuming and expensive. A rapid, inexpensive method of finding shear wave velocity profile at a site is Spectral Analysis of Surface Wave (SASW) method.
Correlating Borehole Data with Electrical Resistivity Test Results
Ravi Sundaram and Sanjay Gupta, 11-Jan-2001

Introduction:On major projects, the geotechnical investigation activity usually involves a variety of different tests. To check the consistency of the results, it is essential that the data from different tests are comparable and lead to similar conclusions. This may be done by theoretical or empirical correlations that should be checked and calibrated using actual field data.

The paper will present the field application of a simple correlation that helps to interpret the litholog from the electrical resistivity test. The interpretation is compared to the actual borehole data. Such a comparison can also be used as a quality check on the resistivity data.

Data from two project sites will be presented. The first project relates to geotechnical investigation for a Captive Power Plant at Raipur (Chattisgarh) and the second one is for a 500 MW Coal based power project at Samalkot (Andhra Pradesh).

Citation : Ravi Sundaram and Sanjay Gupta (2001), Correlating Borehole Data with Electrical Resistivity Test Results, Proceedings, Indian Geotechnical Conference (IGC-2001), Indore, pp 44-47.

ARTICLES
Recent Trend In Foundation Strengthening
Sanjay Gupta,Ravi Sundaram, 01-Oct-2017

Brief:Modern Foundation engineering can come to rescue of structures that have experienced signinficant foundation distress or failure.Detailed investigation of cause and mode of failure together with careful planning and sound engineering practice is the key to successful execution of the foundation strengthening process.Specific case histories of some projects in Delhi and Bihar are described explaining the nature of foundation distress and methodology adopted to stabilize the structures and ensuring adequate foundation Performance.

Pile Foundations Save Transmission Towers At Agra
Sanjay Gupta,Ravi Sundaram, 06-Sep-2017

Brief:The shifting of course of the Yamuna River at Agra by over 800 m during the last four years had threatened the stability of transmission towers of a 220 KV-tansmission line on the river bank.After last year's monsoons ,the river had shifted dangerously close to the existing towers.

Geotechnical Investigations - The Way Forward
Sanjay Gupta,Ravi Sundaram, 19-Sep-2017

Brief:A thorough geotechnical investigation is a pre-requisite for a reliable,safe and economical foundation design.It is important that whatever is envisaged at the investigation and design stage should translate into construction that is in sync with the design concepts,assumptions and predicted foundation behaviour.