Ultimate Comprehensive GEO 3701 Geotechnical
Desktop Study Report for the Ga-Mathipa Room Project
Exam Success, Featuring Two Hundred Practice
Questions and Verified Answers with Detailed
Rationales, Plus South African SANS Regulations,
Dolomite Risk Assessment, and Phase 2 Investigation
Planning Strategies.
SECTION A: DEFINITIONS & CORE CONCEPTS
(Q1 – Q20)
Q1: What is a Geotechnical Desktop Study
(Phase 1)?
• ☑VERIFIED ANSWER: A non-intrusive
investigation that collates and reviews
existing geological, topographical, and
historical data to assess ground conditions
, and identify hazards before any physical site
work begins.
• Rationale: It is the cheapest and fastest way
to screen a site. It determines if a site is
even viable and guides where to dig in
Phase 2.
Q2: What is the primary difference between a
Desktop Study and a Site Investigation (Phase
2)?
• ☑VERIFIED ANSWER: A Desktop Study
involves no physical disturbance of the
ground (desk-based research only), whereas
a Site Investigation involves intrusive
methods like trial pits, boreholes, and in-
situ testing (e.g., DCP).
• Rationale: Phase 1 tells you what to expect;
Phase 2 confirms it physically.
,Q3: Define "Dolomite" in a geotechnical
context.
• ☑VERIFIED ANSWER: A carbonate rock
(calcium magnesium carbonate) that is
soluble in weak acidic groundwater, leading
to the formation of cavities, sinkholes, and
subsidence.
• Rationale: Dolomite land is notoriously
hazardous in Gauteng and Limpopo. A
desktop study must flag this immediately.
Q4: What is "Heave"?
• ☑VERIFIED ANSWER: The upward
movement of the ground surface, typically
caused by the swelling of expansive clays
when they absorb water, or by frost action
(though less relevant in SA).
, • Rationale: Heave exerts upward pressure on
foundations, often exceeding the structural
dead load, causing cracking.
Q5: Define "Collapsible Soils".
• ☑VERIFIED ANSWER: Unsaturated soils
(often aeolian sands or residual granites)
that have a high void ratio and low density.
When wetted (without any change in
applied stress), they undergo a sudden,
large volume decrease (collapse).
• Rationale: In semi-arid Limpopo, these soils
are common. A building could sink just from
a burst pipe.
Q6: What is the "Water Table" and why is it
relevant to a desktop study?
• ☑VERIFIED ANSWER: The upper level of the
zone of saturation in the ground. It is
Desktop Study Report for the Ga-Mathipa Room Project
Exam Success, Featuring Two Hundred Practice
Questions and Verified Answers with Detailed
Rationales, Plus South African SANS Regulations,
Dolomite Risk Assessment, and Phase 2 Investigation
Planning Strategies.
SECTION A: DEFINITIONS & CORE CONCEPTS
(Q1 – Q20)
Q1: What is a Geotechnical Desktop Study
(Phase 1)?
• ☑VERIFIED ANSWER: A non-intrusive
investigation that collates and reviews
existing geological, topographical, and
historical data to assess ground conditions
, and identify hazards before any physical site
work begins.
• Rationale: It is the cheapest and fastest way
to screen a site. It determines if a site is
even viable and guides where to dig in
Phase 2.
Q2: What is the primary difference between a
Desktop Study and a Site Investigation (Phase
2)?
• ☑VERIFIED ANSWER: A Desktop Study
involves no physical disturbance of the
ground (desk-based research only), whereas
a Site Investigation involves intrusive
methods like trial pits, boreholes, and in-
situ testing (e.g., DCP).
• Rationale: Phase 1 tells you what to expect;
Phase 2 confirms it physically.
,Q3: Define "Dolomite" in a geotechnical
context.
• ☑VERIFIED ANSWER: A carbonate rock
(calcium magnesium carbonate) that is
soluble in weak acidic groundwater, leading
to the formation of cavities, sinkholes, and
subsidence.
• Rationale: Dolomite land is notoriously
hazardous in Gauteng and Limpopo. A
desktop study must flag this immediately.
Q4: What is "Heave"?
• ☑VERIFIED ANSWER: The upward
movement of the ground surface, typically
caused by the swelling of expansive clays
when they absorb water, or by frost action
(though less relevant in SA).
, • Rationale: Heave exerts upward pressure on
foundations, often exceeding the structural
dead load, causing cracking.
Q5: Define "Collapsible Soils".
• ☑VERIFIED ANSWER: Unsaturated soils
(often aeolian sands or residual granites)
that have a high void ratio and low density.
When wetted (without any change in
applied stress), they undergo a sudden,
large volume decrease (collapse).
• Rationale: In semi-arid Limpopo, these soils
are common. A building could sink just from
a burst pipe.
Q6: What is the "Water Table" and why is it
relevant to a desktop study?
• ☑VERIFIED ANSWER: The upper level of the
zone of saturation in the ground. It is
