foundation works and soil improvement -...

Foundation Works and

Soil Improvement

Lecture 10

TSP-308 MPK Ferdinand Fassa

To keep the building standing securely, a foundation supports a number of different kinds of loads

• Dead load (of the building)

• Live load (people, furnishing and equipment)

• Wind loads (downward, uplift, or lateral)

• Horizontal pressure of earth and water against basement walls

• Up lift and buoyancy of ground water

• Horizontal and vertical loads caused by earthquake

What do we want from foundation?

Problems with foundation and soil condition

• Settlement • Slope stability • Liquefaction

(after earthquake) • Sinkhole • scouring / abrasion

No Settlement Total Settlement Differential Settlement

effect of liquefaction

landslide (slope Stability)

sinkhole

scouring

scouring / abrasion (?)

Shallow Foundation

Spread footings • Wall footings • Mat foundations / Raft foundations

Blinding (sand, granular, lean concrete)

Construction sequences of shallow foundations

• Excavate dirt down to the desired level

• Install braces or shoring (diaphragm)

• Compact soil

• Spread granular material COMPACTED

• Install formwork

• Install steel reinforcement and anchors

• Pour concrete

• Backfill

construction of footing – beam on grade

Retaining system soldier piles

Retaining system sheet piles

Types pre-stressed concrete; steel; timber

Application cofferdams, riverbank

construction of basement

Bracing for slurry wall / soldier beams / sheet pilling

crosslot bracing

rakers

tiebacks

construction of diaphragm

Construction of slurry walls

EXCAVATING SOIL

SLURRY PUMPED

IN

INSERTING REINFORCING

STEEL CAGE INTO TRENCH

PORUING CONCRETE

INTO TRENCH

SLURRY PUMPED

OUT

COMPATED REINFORCED

CONCRETE PANEL

SOIL EXCAVATED AND REPLACED BY SLURRY

Excavation for Barret Piles

– Pile foundations • Concrete

– Cast-in-place – Pre-cast concrete piles – Pre-stressed concrete

• Steel

– Box – H section – Tube

• Wood / Timber

– Bored Piles – Box foundations / Caissons / Basement

Deep Foundation

Pile Selection Criteria

• Type, sizes and weight of supported structures • Physical properties of soil stratum • Depth of stratum (needs cut off or extension?) • Pile material availability • Number of piles required • Driving equipment • Cost (in-placed) • Durability • Adjacent structures • Depth of water (salt water, splash zone?) • Noise restriction

Timber vs. Concrete / Steel Piles

• Cheaper • Easy to reduce length • Various sizes (diameter & length) • Problem with straightness and constant

diameter • Easy handling (less risk to breakage) • Difficult to extent • Damage / breakage to the head • Non-durable (decay and vulnerable to

biological attack) • Non corrosive

Drilled shaft (bored-piles or caisson)

Add bentonite while retracting steel casing / pouring concrete

Bored Pile – cutting excess pile

Pile Foundation & Pile Driving Equipment

Test Pile

Test type

• Load Test w/ Reaction Piles – To determine load capacity with respect to pile

penetration (settlement)

• Standard Penetration Test – To determine the load applied for hammering

Pile loading test

Pile under test

Isolated datum beam

Secondary beam

Timber crib

Main beam

Load cell

Kenteledge of cast-iron block of concrete

Hydraulic jack

Dial gauge - LVDT

29

FIXED PLATFORM

DIAL GAUGE

HYDRAULIC JACK

REACTION BEAMS

Static Load Test

installation of bulb piles (franki piles) drive steel casing into final depth

pour concrete and compacted

pile driving methods

Vertical

Aft batter

Forward batter

Operating Mechanism of Diesel Hammer

Pile Driving Calculation

• Drop Hammer

• Single-Acting Hammer

• Double-Acting Hammer

10

2

.S

HWR

1.0

2

S

HWR

1.0

2

S

ER

R = safe load on pile (lbs) W = weight of falling mass (lbs) H = height of free falling mass (ft) E = total energy of Ram at the bottom of its down-

strokes (ft-lbs) S = average penetration per blow for last 6 blows (in)

s

h

R

RsWh

Pile Load Capacity

pr

pr

WW

WKWx

S

ER

.

1.0

2

R = safe load (lbs)

S = average penetration per blow, last 6 blows (in.)

E = energy of hammer (ft-lbs)

Wr = weight of hammer ram (lbs)

Wp = weight of pile, incl. driving apparatus (lbs)

K = coefficient of restitution

K = 0.2 for piles weighting 50 lbs or less

K = 0.4 for piles weighting 50 lbs to 100 lbs

K = 0.6 for piles weighting more than 100 lbs

Recommended Hammer Sizes

Size expressed in foot-pound of energy blow The indicated energy is based on driving two steel piles simultaneously. In driving single piles, use approximately two-third of the indicated value

calculation

• Ave. penetration, S = ¼ in./blow

• Depth of stratum = 150 ft

• Driving full penetration thru ordinary soil

• Pile driving energy, E = 15,000 ft-lbs; K = 0.2 • Wp = (50 ft x 40 lbs/ft + 750 lbs) = 2,750 lbs; S = ¼ in / blow = 0.25

• R = (2)(15,000) [3,500 + (0.2)(2,750)] (0.25 + 0.1) [3,500 +2,750]

= 55,543 lbs

Concrete piles • Length of pile = 50 ft

• Unit weight of pile = 40 lbs/lin.ft

• Ram weight, Wr = 3,500 lbs

• Weight of driving app. = 750 lbs

• Determine safe load of hammer (R)

pr

pr

WW

WKWx

S

ER

.

1.0

2

Bulb Piles

L = safe load capacity (tons)

W = weight of hammer (tons)

H = height of drop (ft)

B = number of blows per cu.ft of concrete in driving final batch into base

V= un-compacted volume of concrete in base and plug (cu.ft)

K = constant; depend on soil type and type of pile shaft (9 on gravel to 40 on very fine sand)

K

VBHWR

32

calculation

• Hammer weight, W = 4 tons

• Height of drop, H = 18 feet

• Vol. in last batch driven = 4 cu.ft

• No. blows to drive last batch = 32

• Vol. of base and pug, V = 24 cu.ft

• K value = 15

15

248184 32

R

B = 32 / 4 = 8 blows/cu.ft

Bored pile construction

pour concrete

install reinforcement

Concrete pump

add bentonite

excavation and steel casing

• Excavate soil using auger/drilling bucket

• Install (steel) casing

• Inject bentonite mix to stabilize

• Insert reinforcement (as required)

• Insert tremie pipe

• Place concrete while pumping out bentonite

underpinning

Performance of foundation is influenced by: – Movement during construction – Movement after construction – Response to ground movement

The installation of temporary or permanent support to an existing foundation to

provide either additional depth or an increase in bearing capacity

underpinning

Jacking up

underpinning

Improving non-cohesive soil

42

sand compaction piles

vibrator

casing

driven point (closed) driven point

(open)

sand

vibrator

casing casing

driven point (closed)

driven point (closed) driven point

(open) driven point

(open)

sand sand

Ground Improvement Method

Ground Improvement with Local Material

bamboo mattress piles foundation Tipikal Potongan Melintang

Quarry run/kerikil/sand bagsSeabed

Cerucuk Bamboo

Matras Bamboo 5 lapis

Spasi = 1 m, L = 6 m

Seabed

Tipikal Potongan Melintang



Cerucuk Bamboo



Cerucuk Bamboo



SeabedSeabed

Muara Angke Breakwater

Full-scaled Test Bamboo Mattress Pile

Slope Stability Improvement

SF>1.3SF>1.3

Slope Stability Improvement

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