FOUNDATION PROBLEMS

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Slide 1: 

In the name of Allah, the compassionate, the merciful

FOUNDATION PROBLEMS : 

FOUNDATION PROBLEMS Sohail Kibria M.Sc. Civil Engg. General Manager, Geotech. & Geo-environmental Engg. Division, NESPAK

Slide 3: 

PROPERLY DESIGNED, CONSTRUCTED & DURABLE FOUNDATIONS IN ALL GROUND CONDITIONS ENSURE SAFETY OF BUILDINGS AND THE HUMAN LIVES.

Slide 4: 

MOST OF THE PROBLEMS IN FOUNDATIONS ARISE DUE TO PROBLEMATIC SOILS

UNGLORIOUS ? : 

UNGLORIOUS ? THERE IS NO GLORY IN FOUNDATIONS ………….. Karl Terzaghi

STEP CHILD NOTION : 

STEP CHILD NOTION IN CIVIL ENGG. PROJECTS, THE WORKS OF FOUNDATION ENGG. ARE OFTEN TAKEN AS A STEP CHILD; AND WHEN THE STEP CHILD GOES TO TAKE REVENGE, THE RESULTS ARE VERY NASTY …………. Karl Terzaghi

WHAT ARE PROBLEM SOILS ? : 

WHAT ARE PROBLEM SOILS ? The soils that show abnormal behavior, not recognizable by routine soil testing i. e. by classification, strength, settlement and chemical testing are called problem soils. These soils possess undesirable engineering properties, that may badly affect the structures, if not attended properly.

VARIOUS PROBLEM GROUND CONDITIONS IN PAKISTAN : 

VARIOUS PROBLEM GROUND CONDITIONS IN PAKISTAN Landslide Prone Areas Swelling/Shrinking Soils Dispersive Soils Collapsible Soils Liquefiable Soils Soft Ground/Fill Areas Sheared Clays Soils with Chemicals

WHAT CAN THESE SOILS DO ? : 

WHAT CAN THESE SOILS DO ? SUDDEN / EXCESSIVE SETTLEMENTS TILTING / SINKING OF BUILDINGS CRACKS IN BUILDINGS COLLAPSE OF BUILDINGS CHEMICAL ATTACK ON FOUNDATIONS

ADDITIONAL DIFFICULTIES IN PLANNING / DESIGN / CONSTRUCTION : 

ADDITIONAL DIFFICULTIES IN PLANNING / DESIGN / CONSTRUCTION Space restriction and design modifications Time constraints Resources constraints Excessive variation in ground levels / bedrock levels Abnormal changes in environments after construction

Slide 11: 

PROBLEMATIC SOILS REQUIRE SPECIAL TESTS AND STUDIES FOR THEIR IDENTIFICATION AT SITE & IN THE LAB. SUBSEQUENTLY SPECIAL MITIGATIVE MEASURES WILL BE REQUIRED.

WHERE LOCATED IN PAKISTAN ? : 

WHERE LOCATED IN PAKISTAN ? We can gain from the Chinese and Russian experiences of collapsible soils, Japanese experiences of landslides and liquefiable soils, Indian experiences of swelling soils etc. Some of the areas containing problematic ground conditions in Pakistan include landsliding problems in the northern parts of Pakistran, swelling soils at D .I. Khan, Chakwal, Dera Bugti, Khairpur etc., collapsible soils at Rawat, Hub, Sahiwal etc., liquefiable soils at Chashma, Kalabagh, Kot Addu, Muzaffargarh etc., dispersive soils at Turbat etc. and soft ground conditions in the historical cities like Lahore, Peshawar, Multan, Pakpattan etc. and in the cultivated lands.

LANDSLIDE PRONE AREAS : 

LANDSLIDE PRONE AREAS CAUSES Unstable soils/rocks Water movement Earthquakes EFFECTS Sliding Total Destruction MITIGATION Stabilization of unstable slopes Construction to resist earthquakes Construction in safe areas

Soft Ground/Dumped Fill : 

Soft Ground/Dumped Fill CAUSES Wet lands Agricultural sites Old dumped fills EFFECTS High settlements Cracking/damage of structures MITIGATION Bypassing Replacement Rigid Foundation system/Deep foundation system Prevent water ingress

Swelling / Shrinking Soils : 

Swelling / Shrinking Soils CAUSES Presence of single and double layer minerals in soils attract water and swell Exposure of expansive soils supporting light structures to water EFFECT Map cracking on ground surface in dry weather Swelling with water, causing cracks in light buildings Heaving of floors and pavements Shrinkage will take place in expansive soils upon reduction in moisture MITIGATION Bypassing Replacing Preventing water ingress Rigid foundation system Pre-wetting Lime treatment Deeper foundations

SWELLING CLAY MINERALS : 

SWELLING CLAY MINERALS

IDENTIFICATION OF SWELLING SOILS : 

IDENTIFICATION OF SWELLING SOILS

INDICATION OF DEGREE OF SWELLING : 

INDICATION OF DEGREE OF SWELLING

SWELL MITIGATION AT GOMAL UNIVERSITY, D.I. KHAN : 

SWELL MITIGATION AT GOMAL UNIVERSITY, D.I. KHAN

DISPERSIVE SOILS : 

DISPERSIVE SOILS CAUSES Presence of high Na ions in comparison to total quantity of Na, K, Ca & Mg ions EFFECTS Dispersion of soil grains even in still water Quick erosion of soils Loss of soil cover MITIGATION Provision of protective layer Provision of filters Addition of lime

DISPERSIVE SOILS : 

DISPERSIVE SOILS

COLLAPSIBLE SOILS : 

COLLAPSIBLE SOILS CAUSES In arid/ semi-arid areas, temporary bonds develop between soil grains. These bonds dissolve upon wetting and under pressure EFFECTS Sudden subsidence of soils upon wetting Damage to the buildings on such soils MITIGATION Prewetting Compaction Replacement Rigid Foundation Bypassing such soils Preventing water ingress

COLLAPSIBLE SOIL GRAINS : 

COLLAPSIBLE SOIL GRAINS

USBR COLLAPSE CRITERIA : 

USBR COLLAPSE CRITERIA

COLLAPSE STUDY IN LAB. : 

COLLAPSE STUDY IN LAB.

COLLAPSIBLE SOILS : 

COLLAPSIBLE SOILS

RIGID FOUNDATIONS TO RESIST COLLAPSE OF SOILS : 

RIGID FOUNDATIONS TO RESIST COLLAPSE OF SOILS

LIQUEFIABLE SOILS : 

LIQUEFIABLE SOILS CAUSES Fine to medium sands, under high groundwater table, develop very high pore water pressure under seismic / pulsating loads. EFFECTS The shear strength of soils becomes very low, as the pore pressure rises. Buildings may tilt, sink or get cracked. Loss of life may also occur. MITIGATION Ground improvement by various means Deep foundations Construction on raised ground

GRAIN SIZE OF LIQUEFIABLE SOILS : 

GRAIN SIZE OF LIQUEFIABLE SOILS

EVALUATION OF LIQUEFACTION POTENTIAL : 

EVALUATION OF LIQUEFACTION POTENTIAL

DYNAMIC COMPACTION : 

DYNAMIC COMPACTION

VIBROCOMPACTION : 

VIBROCOMPACTION

GROUTING AND GRAVEL DRAINS : 

GROUTING AND GRAVEL DRAINS

SHEARED CLAYS : 

SHEARED CLAYS CAUSES The presence of fissures causes low shear strength to mobilize at failure The main reason is overconsolidation and the stress relief EFFECTS Low shearing strength called residual strength is available for design Shearing may trigger sliding at low loads MITIGATION The presence of sheared clays can be taken care of, once it is indicated in the lab. Test results

SOILS WITH CHEMICALS : 

SOILS WITH CHEMICALS CAUSES Unleached soils in arid areas Rise of groundwater table, rich in salts EFFECTS Sulphate attack on bricks / concrete Chloride attack on steel MITIGATION Use of appropriate cement Water proofing of substructures Use of rich / impervious concrete mixes Coating of steel

SOME PROJECTS WITH PROBLEM GROUND CONDITIONS : 

SOME PROJECTS WITH PROBLEM GROUND CONDITIONS Gomal University, D. I. Khan Shah Abdul Latif Bhatai Univ., Khairpur Sialkot-Lahore Motorway Project Chashma Nuclear Power Plant Chashma Hydropower Project Galadari Cement Works, Hub Lucky Cement Project, D. I. Khan Akra Kaur Dam Project Pakistan Housing Project New Islamabad International Airport Project Lahore Ring Road Project Lai Expressway Project NUST Campus, Islamabad KKH Upgradation / Reconstruction Project

MITIGATIVE RECOMMENDATIONS : 

MITIGATIVE RECOMMENDATIONS The following broad conclusions are drawn and recommendations are made for the design of safe buildings on problematic sites: For a building project, adequate amount of field and laboratory studies must be carried out to investigate the possibility of the presence of a problematic soil. In case, the presence of a problematic soil is confirmed, supplementary testing for quantification of the relevant parameters must be carried out. The most cost-effective remedial measures must be subsequently evolved, in keeping with the indigenous technology. The engineering institutions must consider launching a comprehensive research program, for a detailed study of problem soils and preparation of national guidelines, for the design of safe buildings in such conditions.

THANK YOU : 

THANK YOU

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