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

Bidirectional Static Load Test – Case Studies
Justin St. George, Ravi Sundaram, Sorabh Gupta, 15-Nov-2018

Abstract

Bi-Directional Static Load Pile Tests (BDSLT) was performed on a barrette pile of dimensions 1.2 m x 2.8 m extending to 21.278 m below the cut-off level. The test load applied was 10,800 tonnes which can usually not be applied by a traditional static load test. The test results indicated that the pile mobilized an ultimate unit skin friction value of 188.4 T/m2 and an end bearing result of 734.5 T/m2. Equivalent load-settlement curve indicates settlement of 4.6 mm at 100% the proposed working load, and 7.8 mm for 150% of the working load.

Keywords: Ultimate Load Test, Working Load Test, Bi-Directional Static Load Test, Skin Friction, End Bearing, Kentledge Test

Citation:

Justin St. George, Ravi Sundaram, Sorabh Gupta (2018), “Bidirectional Static Load Test – Case Studies”, Proceeding DFI India-2018 Conference, Deep Foundations Institute of India, Gandhinagar

Assessing Depth of Well Foundation – Case Study
Ravi Sundaram, Sanjay Gupta, Sorabh Gupta, 17-Nov-2018

Abstract

Parallel seismic test and sonic pulse echo response test are effective non-destructive methods to determine the depth of an existing foundation. The paper presents a case where depth of well foundation installed for a bridge across a drain was questioned by the owner. While the contractor insisted that the well depth was 12.2 m below the well cap as per the drawings, the owner doubted it. The tests provided a scientific basis for confirming the as-constructed depth of the foundation.

Keywords: foundation depth assessment, NDT Testing, Parallel seismic test, sonic echo response test, well foundations

 

Citation:

Ravi Sundaram, Sanjay Gupta, Sorabh Gupta (2018), “Assessing Depth of Well Foundation – Case Study”, Proceeding DFI India-2018 Conference, Deep Foundations Institute of India, Gandhinagar.

Foundations for an Overhead Tank - Forensic Assessment
Ravi Sundaram, Sanjay Gupta, J.T. Shahu and Bappatiya Manna, 13-Dec-2018

Abstract

Understanding the stratigraphy and nature of deposition is paramount for selection of appropriate foundation system for any structure. The paper presents case study of an overhead tank that was planned to be constructed at a site that had a fill of stone stones and boulders to about 7 m depth. A thorough geotechnical investigation with boreholes extending beyond the boulder filling helped generate adequate geotechnical data for a proper assessment of the foundation system required.

Citation:

Ravi Sundaram, Sanjay Gupta, J.T. Shahu and Bappatiya Manna (2018), “Foundations for an Overhead Tank - Forensic Assessment”, Proceedings, Indian Geotechnical Conference IGC-2018, Bangalore

Foundations for Tall Buildings: Geotechnical Aspects - Keynote lecture delivered at IGC-2018
Ravi Sundaram, Sanjay Gupta & Sorabh Gupta, 13-Dec-2018

Abstract

Design of heavily loaded foundations for tall buildings requires a realistic assessment of the design parameters. A comprehensive geotechnical investigation and in-situ tests such as static cone penetrometer tests, pressuremeter tests and cross-hole seismic tests in addition to deep boreholes can provide the inputs for selection of the design profile. The piled-raft concept can yield substantial saving in the design of tall buildings by reducing the number of piles due to the contribution of the intervening soils below the raft. To assess the settlement and load distribution beneath the raft, soil-structure interaction study should be done. A case study of a 38-storeyed building in the Indo-Gangetic Alluvium is presented to demonstrate the quality of data that can be obtained from a thorough geotechnical investigation and to illustrate the concept of piled-raft. While the reliability of the design is enhanced, the savings that can be achieved by such an approach can be substantial.

Keywords:  Tall buildings; Alluvial deposits; Piled-raft foundation; Soil-structure interaction; Pile load tests.

Citation :

Ravi Sundaram, Sanjay Gupta, Sorabh Gupta (2018), “Foundations for Tall Buildings: Geotechnical Aspects”, Proceedings, Indian Geotechnical Conference IGC-2018, Bangalore.

- Keynote lecture delivered at IGC-2018

Building a University on Liquefiable Sands using Dynamic Compaction
Citation:Ravi Sundaram, Sanjay Gupta, Sorabh Gupta(2017), 17-Sep-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

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,

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.