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
Seasonal Variations in Properties of Expansive Soils along a Railway Corridor in Western India
Sanjay Gupta, Ravi Sundaram and Sorabh Gupta, 07-Apr-2018

ABSTRACT:

The properties of expansive soils at shallow depth are influenced by moisture variations due to seepage of water into the soils during rains. The paper presents a case study in western India along a railway freight corridor. Testing on samples collected from boreholes drilled in the pre-monsoon and post-monsoon periods indicate substantial variations in moisture content, undrained shear strength and swell pressure to about 3-3.5 m depth. Below this depth, these properties show insignificant change. This confirms that the active zone, the geotechnically unstable zone in expansive soils that undergoes swelling-shrinkage due to moisture variations extends to about 3.5 m depth.

Citation : Sanjay Gupta, Ravi Sundaram & Sorabh Gupta (2018), “Seasonal Variations in Properties of Expansive Soils along a Railway Corridor in Western India”, Proceedings, International Symposium on Geotechnics for Transportation Infrastructure (ISGTI-2018), New Delhi, India.

Geotechnical Evaluation of a Landslide in the Lesser Himalayas
Ravi Sundaram, Sorabh Gupta, Rudra Budhbhatti & Kinjal Parmar, 07-Apr-2018

ABSTRACT:

A landslide at Birahi in Chamoli District of the Lesser Himalayas had affected traffic along NH-58. The paper presents details of the geotechnical and geophysical investigations done to evaluate the failure and to develop remedial measures. A slide-zone of overburden with boulders was clearly identified which matches well with the borehole data. The probable causes of failure and remedial measures such as drainage planning, erosion control and reinforcement on valley side are discussed.

Citation : Ravi Sundaram, Sorabh Gupta, Rudra Budhbhatti & Kinjal Parmar (2018), Geotechnical Evaluation of a Landslide in the Lesser Himalayas, Proceedings, International Symposium on Geotechnics for Transportation Infrastructure (ISGTI-2018), New Delhi, India .

Geotechnical Design Parameters for a Metro Tunnel from Pressuremeter Tests
Ravi Sundaram, Sanjay Gupta, Sorabh Gupta & Bhajan Lal, 07-Apr-2018

ABSTRACT:

Being an in-situ test, the pressuremeter provides a reliable assessment of soil parameters, eliminating the influence of sample disturbance. The paper outlines analysis of pressuremeter data to interpret parameters such as undrained shear strength, pre-consolidation pressure, over-consolidation ratio and in-situ horizontal stress. The test was used effectively in conjunction with borehole data to assess the geotechnical parameters for design of a metro tunnel. Data from two locations along the metro tunnel alignment are presented here.

Citation : Ravi Sundaram, Sanjay Gupta, Sorabh Gupta & Bhajan Lal (2018), Geotechnical Design Parameters for a Metro Tunnel from Pressuremeter Tests”, Proceedings, International Symposium on Geotechnics for Transportation Infrastructure (ISGTI-2018), New Delhi, India

Building a University on Liquefiable Sands using Dynamic Compaction
Citation:Ravi Sundaram, Sanjay Gupta, Sorabh Gupta(2017), 09-Oct-2017

Abstract :A major University project spanning 511 acres with a total constructed area of 357 acres has recently been constructed in the state of Uttar Pradesh in North India.

Loose to medium dense ‘clean’ Yamuna sands belonging to the “Indo-Gangetic Alluvium” were encountered at the project site, which were found to be susceptible to liquefaction to about 8-12 m depth. To avoid the difficulties and high costs associated with high-quality soil sampling and advanced laboratory testing for determination of cyclic resistance ratio (CRR), field tests consisting of standard penetration tests (SPT) and cone penetration tests (CPT) were carried out.

Citation:Ravi Sundaram, Sanjay Gupta, Sorabh Gupta(2017),"Building a University on Liquefiable Sands using Dynamic Compaction",9th International Conference on Soil Mechanics and Geotechnical Engineering (ICSMGE 2017)(17 to 22 September 2017), Seoul, Republic of Korea

Identifying Defects in Deep Bored Piles - Case Studies from India
Sanjay Gupta, Ravi Sundaram and Sorabh Gupta, 18-Sep-2017

ABSTRACT:

One of India’s tallest residential towers is being constructed in the state of Uttar Pradesh, not very far from the Yamuna River. The development includes the construction of a 66-story residential tower rising about 240 meters above grade and having two basements extending about 9 meters below grade. The foundation system for the proposed development consists of a piled-raft system with a 2.5-meter thick reinforced raft, supported by 298 Nos. bored-cast-in-situ piles of 1 m diameter and 48 m depth. This paper describes the geotechnical investigations carried out at the project site to estimate the safe pile capacities, and presents the results of a rigorous quality assurance program executed by the authors to ensure foundation quality and performance in-situ. 

Citation : Sanjay Gupta, Ravi Sundaram and Sorabh Gupta (2017), Identifying Defects in Deep Bored Piles - Case Studies from India, Proceedings, 19th International Conference on Soil Mechanics & Geotechnical Engineering (19th ICSMGE-2017), Seoul, Korea. Pages 2637 to 2640.

Geotechnical Investigation across a Failed Hill Slope in Uttarakhand – A Case Study
Ravi Sundaram, Sorabh Gupta, Swapneel Kalra, 13-Dec-2017

ABSTRACT:

A landslide triggered by a cloudburst in 2013 had blocked a major highway in Uttarakhand. Thepaper presents details of the geotechnical and geophysical investigations done to evaluate thefailure and to develop remedial measures. Seismic refraction test has been effectively used to characterize the landslide and assess the extent of the loose disturbed zone. The probable causes of failure and remedial measures are discussed.

Citation : : Ravi Sundaram, Sorabh Gupta, Swapneel Kalra (2017), “Geotechnical Investigation across a Failed Hill Slope in Uttarakhand – A Case Study”, Proceedings, Indian Geotechnical Conference-IGC (14-16 December, 2017), IIT Guwahati

Building a Mega Power Plant on Liquefiable Sands- A Case Study
Sanjay Gupta, Ravi Sundaram, Sorabh Gupta, 14-Aug-2016

Abstract : Geotechnical investigation for a major power plant in Punjab indicated the likelihood of liquefaction of the loose sands to about 7.5-11 m depth. To mitigate the liquefaction potential, ground improvement by vibro-compaction was done for the light to medium loaded facilities. Piles extending well below the liquefiable zone were used to support heavily loaded facilities. The paper presents data and analysis for the Boiler-I area where ground improvement was done successfully done and raft foundation for the raft was provided.

Citation : Sanjay Gupta, Ravi Sundaram, Sorabh Gupta (2012), “Building A Mega Power Plant On Liquefiable Sands – A Case Study”, Proceedings of Indian Geotechnical Conference (December 13-15, 2012), Delhi, Page 428 to 431.

Current Trends IN Geotechnical Investigation Techniques
Sorabh Gupta, Ravi Sundaram, Sanjay Gupta, 08-Apr-2016

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 and aquifer test.

Citation : Sorabh Gupta, Ravi Sundaram, Sanjay Gupta (2016), “Current Trends in Geotechnical Investigation Techniques”, AGE-2016, National Conference on Advance Geotechnical Engineer (April 8th-9th April, 2016), Aligarh Muslim University, Aligarh, Pages 37 to 52.

Piles Through Soft Clay For A Metro Project
Ravi Sundaram, Sanjay Gupta, Sorabh Gupta, Abraham V. Varghese, 08-Sep-2016

Abstract : Geotechnical investigation for the Kochi Metro revealed a critical section of the Viaduct near Ernakulam Junction Railway Station. Four piers, located over a 220 m stretch, were passing through an area with substantial thickness of soft clay. The scope of the geotechnical investigation included two boreholes and a static cone penetration test at each pier location. In the boreholes, field vane shear test was conducted at different depths in addition to the routine SPT. The design of heavily loaded piles in such strata is a challenge due to the liquefaction of the shallow sands and negative skin friction / down-drag in the soft under-consolidated clay. Bored cast-in-situ piles of 1500 mm diameter extending to 50-60 m depth were used to carry 500-600 tonnes load.

Citation :Ravi Sundaram, Sanjay Gupta, Sorabh Gupta, Abraham V. Varghese (2016), “Piles Through Soft Clay For A Metro Project ”, Proceedings, DFI India 2016: 6th International Conference on Deep Foundation Technologies for Infrastructure Development in India(September 8-10,2016), Shibpur, Kolkata 

FOOTING LOAD TESTS ON SAND: VALIDATING THEORETICAL PREDICTIONS
Sanjay Gupta, Ravi Sundram & Sorabh Gupta, 17-Dec-2016

ABSTRACT:

As structures get taller and the load demand on the foundation soils increases, it has become imperative to reconsider conventional geotechnics, and calibrate and validate our theoretical predictions with ground conditions. A prototype footing load test was conducted on a 2 m x 2 m size concrete footing for a better assessment of the load-settlement behavior at a site in Noida. This paper presents the test results and compares them to results from conventional methods of analysis. A numerical simulation of the test conditions has also been performed using finite element method to validate the field results with mathematical simulation. It has been found the results of the field test are in good agreement with theoretical predictions, thus enhancing the factor of reliability of our foundation analysis.

Citation : Sanjay Gupta, Ravi Sundaram, Sorabh Gupta (2016), “Footing Load Tests on Sand: Validating Theoretical Predictions”, Proceedings, Indian Geotechnical Conference-IGC-2016, Chennai

 

In-situ Testing to Verify Ground Improvement
Mr. Ravi Sundaram & Mr. Sanjay Gupta, 20-Oct-2015

Abstract: Reliability of improvement achieved is the key to the implementation of soil stabilization and ground improvement measures. In-situ tests are an essential part of the ground improvement process to confirm that the desired improvement in soil properties has been achieved. The paper presents two case studies in the Delhi-NCR area where ground improvement was done to mitigate liquefaction potential and improve the soil bearing capacity. In-situ tests conducted before and after improvement to verify the effectiveness of improvement include SPT (in boreholes), static cone penetration tests (SCPT) and plate load tests.

Citation: Ravi Sundaram, Sanjay Gupta (2015), “In-Situ Testing to Verify Ground Improvement”, Proceedings, Symposium on “Advances in Instrumentation, Geo-Monitoring and Validation”, 23-24 July, 2015), New Delhi

Ndt Techniques for Determining Depth of Foundations
Sanjay Gupta, Ravi Sundaram, Sorabh Gupta, 17-Dec-2015

Abstract : Evaluating the depth of existing foundations may sometimes be required on construction projects. If original pile records / drawings are not available, it may become difficult to make a rational assessment of the depth of existing foundations. Where the new construction requires knowledge of length of pile / depth of existing foundation, modern NDT techniques such as parallel seismic and sonic echo / impulse response tests can provide useful information.

Citation :Sanjay Gupta, Ravi Sundaram, Sorabh Gupta (2015), “NDT Techniques for Determining Depth of Foundations”, Proceedings of 50th Indian Geotechnical Conference (December 17-19, 2015), Pune, Maharashtra,

Back Analysis of Pile Load Test Results a Case Study
Ravi Sundaram, Sorabh Gupta, 23-Jul-2015

Abstract: Caution is required in selecting the safe load carrying capacity of bored piles, even if a few test piles indicate substantially higher capacity than theoretically estimated from static analysis. The consequences of failure of working piles should be evaluated carefully to select suitable safe load carrying capacity for design. Use of pile capacities higher than the computed values should be backed up by sufficient static and dynamic pile load tests and integrity tests. A case study illustrating static and dynamic load tests on piles installed in alluvial sands demonstrates the design methodology to be followed.

Citation : Ravi Sundaram, Sorabh Gupta (2015), “Back-Analysis Of Pile Load Test Results – A Case Study”, Proceedings, Symposium on “Advances in Instrumentation, Geo-Monitoring and Validation”, 23-24 July, 2015), New Delhi

 

Geotechnical Investigation in Gravel-Boulder Deposits
Sundaram, Sanjay Gupta, 04-Dec-2015

Summary : Geotechnical investigation through gravel-boulder formations poses difficulties due to the problems of drilling in such deposits. Various drilling methods such as percussion, rotary and DTH have been used on projects with different degree of success; a combination of two methods is usually effective. In addition to drilling, geophysical tests and load tests help in better assessing the stratigraphy and selecting suitable values of safe bearing capacities.

Citation : Sundaram, Sanjay Gupta (2016), “Geotechnical Investigation in Gravel-Boulder Deposits”, The Bridge & Structural Engineer, Journal of the Indian National Group of International Association for Bridge and Structural Engineering, B&SE (December, 2015), Volume-45, No. 4.

Building a University on Liquefiable Soils Using Dynamic Compaction
Ravi Sundaram, Sanjay Gupta, Sorabh Gupta, 16-Jul-2014

Abstract :A major University site spanning 511 acres with a total constructed area of 357 acres has recently been constructed in the state of Uttar Pradesh in north India. The campus, once established, shall boast of over 84,000 m2 of constructed area with 30 percent green cover. The site is located in the Yamuna flood plain, about 2 km. from the river.

Citation: Ravi Sundaram, Sanjay Gupta, Sorabh Gupta (2014), “Building a University on Liquefiable Soils Using Dynamic Compaction”, Proceedings of DFI Conference (September 19-20, 2014), Delhi, Page 67.

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.