GEOTECH PRESENTATION FOR GEOCON

GEOTECHNICAL REPORT OF ARJA-TIAN-DHALKOT HYDROPOWER PROJECT AZAD KASHMIR(BAGH)

INTRODUCTION

M/S Geo-con were awarded the project of sub soil investigation with geological mapping, topographic survey, seismic survey and interpretation of Harighal-Dhalkot hydropower project

INTRODUCTION CAN’T

In ARJA-TIAN-Dhal kot hydropower project the small reservoir is located on Mahel River upstream. The objective of this small dam is to provide the hydropower downstream the river around the loop through an underground tunnel for power generation

LOCATION AND ACCESSIBILITY

The project area is approximately 10 km from Bagh towards Rawalpindi

The approach of this project area is very easy on Rawalpindi-Bagh main metalled road

In our project area the right abutment of the dam is in district Bagh and the left abutment is in district Poonch and power house is in district poonch

INVESTIGATION PLANE

A programme of subsurface investigation was conducted according to instruction by consultant M/s RENCON, ISLAMABAD

The programme consisted of geological mapping, seismic refraction survey of dam site and power house site as well as collecting subsurface data.

The subsurface data has been collected by drilling and coring in bore holes

INVESTIGATION PLANESr. No. BOREHOLE NO. DEPTH

1. RA#01 30m/Right abutment



4. NB#01 30m/Bed of river

5. NB#02 30m/bed of the river

6. LA#01 30m/Left abutment

7. PH#01 30m/power house

GEOLOGY OF THE AREALITERATURE REWIEW

TWO TYPE OF FORMATION ARE PRESENT IN THIS AREA

SAWALIK FORMATION

MURREE FORMATION

SIWALIKS GROUP

The left abutment of the project have siwalike formation

In this area lower siwaliks and lower part of middle siwalike are exposed. The siwaliks of this area however appears similar throughout. They are petro graphically indistinguishable. The sand stone are coarse grained massive and even pebbly. They are interbeded with hard and compact shaly/clayly rock

STRATIGRAPHIC COMMITTEE OF PAKISTAN

(1973) HAS FORMALIZED SIWALIKE GROUP AND

DIVIDED IT INTO FOLLOWING FORMATION

Soan formation Pleistocene

Dhok phatan formation Pliocene

Nagri formation upper Miocene

Chinji formation middle Miocene

MIDDLE SIWALIKE NAGRI STAGE

Orange and brown incoherent sandstone with harder cores within, weathering in uneven pitted surface. Soft red shale's with buff or grey plant bearing shale's. Hard semi nodular pale red clay, Rhinocerotid and ungulate bones

CHINGI AND NURPUR STAGES

Fine grain, blue grey nonmicaceous sand stone pseudo-conglumerate at interval, massive and thick bedded. Grey coarse, soft micaceous sand stone with pebbles at places almost conglomerates. Strata rudely bedded with laminated shale's hard, indicated, reddish purple, semi concretionary, thickly veined with calcite few calcareous red clays, weathering in hummocky surfaces proportion of sand stone to shale is about equal

KAMLIAL AND LOWER CHINJI

Fewer shale of grey blue, purple and red colors, with carbonized leaf impressions limonitised woody tissues. Hard semi-nodular sand stone blue grey with purple stains, containing kankar like nodules and limonitoised woody tissues (coniferous) proportion of sandstone to shale

RECENT ALLUVIUM

The gentle slopes and flat plains of the area contains stream. River and wind blow the deposits of recent age. The surrounding area of this dam is situated over the alluvial deposits of Mahl river these deposits are composed of clay fine silt and sands with boulders and pebbles of varying size and composition the boulders are usually sub angular to sub rounded the alluvial deposits provide fertile land for agriculture purpose

MURREE FORMATION:

Lithology, the widely exposed rocks of Murree formation is composed of alternating beds of clays, shale, siltstone and sandstone. This formation is well exposed in Rawalakot, Bagh and Hajera areas.

MURREE CLAYS AND SHALE

The Murree clays and shale are red, brown, purple and grey in color, soft, sticky and slightly silty and places

The clay stone is well stratified, brownish grey to dull red, soft to medium hard and interbeded with silt stone and sandstone beds.

MURREE SILTSTONE

The siltstone is greenish grey to pale and yellowish brown on weathered surface

Greenish grey to brownish grey on fresh surface

Thin to medium bedded, at places lens form, soft to medium hard, sheared and fractured.

MURREE SANDSTONE It is greenish to brownish grey and purplish on

weathered surface

Dull down to red and light green to grey on fresh surface

It is massive too thin bedded, fine to medium grained, well sorted and at places cross bedded. It is medium hard to hard, well jointed and fractured

The block size ranges from 2-3m. Joints are mostly closed and packed with secondary clay material. Calcite veins are occasionally present.

QUATERNARY DEPOSITS

The Quaternary deposits include the stream channel deposits, alluvium and some exposures of Mirpur Conglomerate. The stream channel deposits comprise sand, silt, gravel and boulders of unsorted and heterogeneous nature occupying the nala beds and flood plain area. The alluvium consists of mainly clay and silt intermixed with talus and detrital material which is dusky grey to light brown in color. Valleys are filled with alluvial material which is dominantly clay. The slopes have been developed into alluvial terraces

QUATERNARY DEPOSITS

The Mirpur conglomerate is exposed in Bagh area along the Mahl River. It is poorly sorted and consists of pebbles and boulders of sedimentary, igneous and metamorphic rocks indurated in sandy and clayey matrix. These deposits rest with an angular unconformity on Murree formation.

TECTONICS OF THE AREA

Himalayan seismic zone

Suliamn-KirtharSeismic Zone

Kuchch SeismicZone

Makran Seismic Zone

Chaman-HindukushSeismic Zone

PROJECT AREA

PHASING AND OBJECTIVE

The investigation for Arja-Tian-Dhalkothydropower project and its associated structures may initially be directed at choosing the more favorable site. This involve geology and geotechnical study and other aspects

OBJECTIVE

FOLLOWING OBJECTIVE WERE UNDER CONSIDERATION

Engineering parameters, suitability of weir foundations, and its probable settlement which can occur

Seepage problems under the weir and abutments, and to determine the parameters require accessing the volume of seepage, the accompanying pressure distributions, reduce seepage etc.

To examine the water tightness of the reservoir

area and stability of the surrounding slopes under

submergence and draw down.

INVESTINGATIONG AT SELECTED SITE AND DATA EVALUATION OF BOREHOLE LOGS

WEIR SITE:

BORE HOLE RA-01

In borehole RA-01 rocks are slightly fragmented

Slightly too closely jointed

Slightly to moderately weathered

RQD values range from 0 %-78%.

Core recovery range from 60%-97%

RQD IN BORE HOLE RA-01

The RQD value of the upper mudstone is 0-53%

In the lower mudstone bed it is 53%

In upper sandstone bed it is 53-60%

In lower sand stone bed it is 69-72%

CORE RECOVERY IN BORE HOLE RA-01

Core recovery in upper sandstone bed is 60%

Core recovery in lower sandstone bed is 80-97%

Core recovery is 60% in the upper mud stone bed and 63% in the lower mudstone.

LITHALOGY OF BORE HOLE RA-01

The lithology varies as upper shale brownish fine gained

Sandstone is brownish to grayish brown, fine to medium grained and moderately weathered

The middle mudstone is dark brown, fine grained, loose and disintegrated at water contact

BORE HOLE RA-02

Rocks were highly fragmented

Weathered

Highly jointed

The joints were closely spaced

Core recovery value range from 57%-97%

RQD values range from 30%-81%


The RQD value of the upper sandstone is 0-68%

In the lower sandstone bed it is 71-77%

In upper mudstone bed it is 41-76%

In lower mudstone bed it is 53-81%


Core recovery in upper sandstone bed is 77-85%

Core recovery in lower sandstone bed is 66-82%

Core recovery is 73-93% in the upper mud stone bed and 75-98% in the lower mudstone.

LITHALOGY OF BOREHOLE RA-02

Top 1.5m is overburden brownish, grayish brown, coarse grained, gravels, cobbles, pebbles, and some shaly clay

The middle part Reddish brown to brown fine grain highly fractured, freshly weathered s.st.1.5-5m

From 5-15.5m Fractured, medium Compacted, Low strength Mud stone Fractured, jointed and contact of gray Fragmented Mud stone Highly jointed

BORE HOLE RA-03

The rock was slightly to highly fragmented

the joints spacing was moderately to closely the joints direction was along the direction of strike.




The RQD value of the sandstone is 13-76%

The RQD value of mud stone is from30-33%


Core recovery of sand stone is from 34-97%

Core recovery of mudstone is from 53-63%

LITHALOGY OF BORE HOLE RA-03

1-2m is overburden which is reddish brown clay and some cobble

2-27.5m there is highly fractured, weathered reddish brown to brownish fine to medium grain sand stone which is low to medium hard

27.5-30 there is mixture of mudstone and clay that mudstone is medium to highly fractured

BORE HOLE NB-01

The rock was fragmented moderately to highly

Joint spacing was moderately to closely

weathering was slightly to highly

RQD IN BORE HOLE NB-01


The RQD value of mud stone is from 64-84%

CORE RECOVERY IN BORE HOLE NB-01



LITHALOGY IN BORE HOLE NB-01

From 1-16.75m there is gravel poorly sorted and poorly to well rounded

From 16.75-28.2m there is sandstone which is which is jointed, weathered and medium hard

From 28.2-30m there is mud stone which is medium hard

BORE HOLE NB-02

The rock was fragmented moderately to highly

Joint spacing was moderately to closely

weathering was slightly to highly

RQD IN BORE HOLE NB-02


The RQD value of mud stone is from 39-45%

CORE RECOVERY IN BORE HOLE NB-02



LITHOLOGY OF BORE HOLE NB-02

1-20m there is gravel which is poorly to well sorted and medium to well rounded

From 20-27.90m there is sand stone which is medium to fine grained and highly fractured and weathered, color is grey to brownish

From 27.90-30m there is fine grain and highly mud stone whose strength is medium to high

BORE HOLE LA-01

The rock was highly fractured and freshly weathered



RQD IN BORE HOLE LA-01


The RQD value of mud stone is from34-55%

CORE RECOVERY IN BORE HOLE LA-01



LITHALOGY OF BORE HOLE LA-01

1-2m is overburden which is reddish brown clay and some silt

2-28m there is highly fractured, weathered reddish brown to brownish grey fine to medium grain sand stone which is low to medium hard

28-30 there is mixture of mudstone and clay that mudstone is medium to highly fractured

POWER HOUSE SITE

In power house site only one hole was drilled named as PH-01

BORE HOLE PH-01

Silty sandstone ,freshly weathered and highly fractured,

Core recovery value range from 24-93%

RQD value range from 0-81%

Highly fractured mud stone is present which is mixed with clay

LABORATORY TESTING OF DAM SITE

LABORATORY TESTING ON THE ROCK SAMPLES

TESTING LABORATORY

The laboratory testing on the rock sample was got done from rock mechanics laboratory of mining engineering department university of engineering and technology Lahore

TEST TYPE

Two type of test were performed on rock sample

Test For Physical Properties

Test For Mechanical Properties

PHYSICAL PROPEERTIES TEST

Following properties was determine

Moisture content

Porosity

Density

DISCUSSION OF PHYSICAL PROPERTIES OF ROCK SAMPLE IN DIFFERENT BOREHOLES

BORE HOLE RA-01

In bore holes RA-01 the average moisture content was .509% average porosity measured by helium porosimeter was 10.3%. Average density was 2.601 gm/cc

BORE HOLE NB-01

In bore hole NB- 01 the average moisture content was .280% average porosity measured by helium porosimeter was 4.47%. Average density was 2.646 gm/cc

BORE HOLE LA-01

In bore hole LA- 01 the average moisture content was 0.530% average porosity measured by helium porosimeter was 9.49%. Average density was 2.610 gm/cc

MECHANICAL PROPERTIES

Following test was done for the mechanical properties of the rock sample

UNIAXIAL COMPRESSIVE STRENGTH

DISCUSSION OF MECHANICAL OF ROCK SAMPLE PROPERTIES IN DIFFERENT BOREHOLES

BORE HOLE RA-01

The average height of the sample was 110.00mm and the average diameter was 43.75mm. height to diameter ratio was 2.51 which is according to ISPR standard

Moisture conditions of the specimen at the time of test were laboratory air dry. The equipment used for this test was universal testing machine. The unconfined compressive strength of the sample was 107.985MPa

BORE HOLE NB-01

The average height of the sample was 110.00mm and the average diameter was 44,00mm. Height to diameter ratio was 2.52 which is according to ISPR standard


BORE HOLE LA-01

The average height of the sample was 110.00mm and the average diameter was 43.40mm. Height to diameter ratio was 2.53 which is according to ISPR standard


PETROGRAPHIC TEST ON ROCK SAMPLE

TESTING LABORTARY

MINERALOGY LAB PUNJAB UNIVERSITY LAHORE

Petrographic only done at the sample from NB-01 at the depth of 20-21m. The core samples have diameter 4cm and length 25cm, weight 800gm. At the cut surface, the color of the sample is medium grey, the sample show mild effervescence at the surface on reaction with cold dilute HCl. Megascopic assessment of the sample revealed that the core sample is fine grained sand stone.

DISCUSSION OF MINERALOGY OF ROCK SAMPLE

Following is the mineralogical composition of the sample

QUARTZ 61%

FELDSPAR 20%

LITHIC FRAGMENTS 7%

CALCITE 7%

MUSCOVITE 3%

MAGNETITE 2%

CHEMICAL ANALYSIC OF WATER SAMPLE

Water sample was taken from NB-01 and NB-02 of dam site. There chemical analysis shows that water does not contain sulphates or any other dangerous property in harmful quantity. As such ordinary Portland cement may be used in the foundation.

LABORATORY TESTING ON THE SOIL SAMPLES

Testing Laboratory

The laboratory testing on the soil samples was got done from the geo-technical engineering Laboratory of civil department University of Engineering & Technology Lahore.

COLLECTION OF SAMPLES

Two samples of insitu soil were collected from the site. One sample from RA-01 and other sample from PH-01. The sample from RA-01 was collected from 2-3m depth below existing ground level during July 2013. The sample PH-01 was collected from 6-7m depth below existing ground level during September 2013.

LABORATORY TESTING

Both the samples were sent to university of engineering & technology Lahore for soil classification. Following tests were carried out on these samples.

Grain size analysis – ASTM D422

Atterbergh limits – ASTM D4318

DISCUSSION ABOUT TEST RESULTS

Both the samples were found to be non plastic in nature. The sample of RA-01 is classified as silty sand (SM) & sample of PH-01 is classified as poorly graded sand with silt (SP-SM) as per unified soil classification system ASTM D-2487.

RECOMMENDATIONS

Sandy soil is a good bearing material provided that it is properly compacted & confined. In open areas without confinement, this type of material is subjected to erosion. Without proper confinement erosion cannot be avoided. It is therefore suggested that proper confinement of this material be done to avoid the direct hit of water.

FIELD TEST IN DRILL HOLE

Permeability in rock strata has been determined during drilling operation using in-situ water pressure test in drill hole for weir and operational structure

CONCLUSIONS AND RECOMMENDATIONS

Geological investigations of ARJA-TIAN-DHALKOT HPP suggest that site is feasible taking into consideration the discontinuities present

To thoroughly investigate the geological and structural conditions of the tunnel and dam site area extra geotechnical study are require in the tunnel site and dam site During construction stages

The grouting of Joints and fractures will increase the stability of rocks.

Seismicity of the area must be considered during the design of foundations for dam.

Construction material is available nearby dam site so this will be economical for the construction of dam, but for power house and tunnel the accessibility of material will be difficult

Flooding in rainy season is very high in river, the effects must be considered during the design and after constructions of dam.

Because of medium to high relief of mountains, erosion effects are expected, so sedimentation factor should be considered while designing the dam

Thick sandstone with subordinate siltstone and shale is commonly exposed at the surface, or at the shallow depth throughout the area. The foundation therefore may be laid down on the fresh rock. Overburden and weathered portion should be removed

Core recoveries and RQD value is good enough and it reveals from laboratory results. That the rock is hard enough to sustian the expected load of the structure.

Rocks of catchment area are belonging to siwalike group, which is characterized by alternate beds of sandstone and shale. The later unit is soft, therefore siltation activity is expected

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GEOTECH PRESENTATION FOR GEOCON